A Short History of the Lunulite Bryozoa

BULLETIN OF MARINE SCIENCE, 33(3): 566-581, 1983

A SHORT HISTORY OF THE LUNULITE BRYOZOA

P. L. Cook and P. J. Chimonides

ABSTRACT The "lunulites" include two highly convergent, very specialized families of Bryozoa. Their cup-shaped colonies live freely on the surface of sediments, supported, stabilized and cleaned by elongated mandibles of polymorphic member zooids (avicularia), which are also the means of locomotion in some species. Living species of the Family Lunulitidae are known only from Australasian "sand fauna" environments, but abundant faunas are known from the European Cretaceous-to-Pliocene, and the Tertiaries of West Africa, America and Australasia. The Family Cupuladriidae had a similar Tertiary distribution, and is now found worldwide in sand fauna environments, including those of Australia. The distinctive environmental parameters of the lunulites, together with inferred distributions of palaeocurrents and continental plates, are used to test the feasibility of routes and rates of dispersal, and the reasons for extinctions and isolations of faunas in space and time. A few elements of the Recent Australasian fauna may have resulted from episodes of Palaeocene and Miocene migration from Tethyan stocks, but most species appear to be descendants of forms isolated from a once widely distributed, circum-Antarctic fauna. This may have originally dispersed from Central America in several episodes, and by different routes, since the Palaeocene.

The living Australasian bryozoan fauna includes many genera and some species which have a Tertiary-to-Recent range. In addition, some Recent Australasian genera have representatives in early Tertiary deposits remote from their present distribution (Lagaaij and Cook, 1973; Cook and Lagaaij, 1976). It is also becoming increasingly evident that genera previously considered to have a purely Austral- asian distribution, sometimes as Tertiary fossils only, have a much wider range in time and space (Hayward and Cook, 1983). Apparent descendants of the Eu- ropean Cretaceous and Tertiary free-living genus Lunulites, in particular, are now found only in Australian waters. Current investigation of the systematics of Lu- nulites, and of two other closely related genera, Otionella and Selena ria, has led to a study of the distribution of the Family Lunulitidae from the Cretaceous to the present. In addition, the history of the systematically distinct, but highly convergent, free living Family Cupuladriidae complements and supplements that of the Lunulitidae. The historical biogeography of these two families, informally called the lunulites, is discussed here. Although there are widely differing views of the function of biogeographical studies (Ekman, 1967; Humphries, 1981), no general synthesis of a Recent fauna is complete without preliminary detailed analysis of its component elements in time and space (Lagaaij and Cook, 1973). Among sessile invertebrate phyla, Recent distributions may be much less completely known than the fossil record, and frequently species have never been observed alive in situ or in the laboratory. Collection bias is also a significant factor in the study of small, shallow-shelf, marine animals, where finds are often fortuitous. Once an animal has been found in one strong association, there is also an overwhelming tendency to search for amplification in that association alone, simply because there would then be a high chance of success (Cook, in press). This is particularly true for animals which have no apparent potential for commercial exploitation, or no already established reputation for scientific significance.

566 COOK AND CHIMONIDES: HISTORY OF LUNULITE BRYOZOA 567

STRUCTURE AND ECOLOGY OF LUNULITES The lunulite bryozoans have been extensively studied from areas of geosynclinal subsidence, particularly from oil-well drillings and marine sediments, and large numbers of records are therefore available. Colonies are often abundant and are distinctive and easily recognized; they are therefore often recorded in surveys where other Bryozoa are not distinguished. The environmental parameters of living species are well defined, and colonies have been observed both in the sea and in the laboratory. A study of lunulite biogeography can therefore draw on more sources of information than are often available in investigation of other bryozoans (Marcus and Marcus, 1962; Cook, 1963; Lagaaij, 1963; Cullen, 1967; Greeley, 1967; Buge, 1975; Cadee, 1975; Hakansson, 1975; Cook and Chimon- ides, 1978; Chimonides and Cook, 1981). The lunulitiform colony morphotype is found only among cheilostome bryozoans, where member zooids possess an operculum. In feeding zooids (autozooids) this covers the orifice, but in some specialized, usually non-feeding polymorphic zooids (avicularia), the operculum (termed the mandible), is variously enlarged and modified for defense, cleaning or support (Ryland and Hayward, 1977; Hay- ward and Ryland, 1979; Cook, 1979a). Lunulitiform colonies are cup or saucer- shaped, and bear zooid orifices on the convex surface. This morphotype has been independently evolved in members of a wide range of unrelated families. Many lunulitiform colonies develop basal cuticular rootlets on the concave surface, which anchor them into the upper layers of sediments (Cook, 1979b; Cook and Chimonides, 1981). The lunulites are distinct in that they are free-living and possess no rootlets. Colonies are supported and stabilized on the surface of sediments by the elongated, paddle-shaped or bristle-like mandibles of the latest developed, peripheral and subperipheral avicularia. All mandibles are involved in unburying colonies cov- ered by sediments, or in regaining 'normal' orientation if reversed. In one genus, Selenaria. mandibles are the means of colony locomotion (Marcus and Marcus, 1962; Cook, 1963; Greeley, 1967; Cook and Chimonides, 1978; Chimonides and Cook, 1981). Avicularia are therefore of great importance in the specialized mode of life of lunulite colonies, and enable them to inhabit areas generally unsuitable for many other sessile animals, including bryozoans (Cook, 1968a; in press). All lunulites, together with rooted lunulitiform species and other, specially adapted rooted forms are found together in areas of sandy or muddy sea-bottoms (Cook, 1979b). Some of these 'sand faunas' are from very deep water (Cook, 1981), but the great majority is found in shallow-shelf, warm seas. Autochthonous fossil sand fauna assemblages often include the same range of rooted and free-living genera as living faunas. Together with independent evidence from other animal groups, this allows the confident inference that the past environments were not materially different from those inhabited by living forms today (Cook and Lagaaij, 1976). Although the shallow-shelf areas of the world's seas have only been sporadically surveyed for bryozoans, enough is known to enable definition of the environmental parameters controlling lunulite occurrence negatively and positively. Negatively, it is known that lunulites are absent from rocky areas of high turbulence, from coarse shell or pebble beds, from waters with salinities above 370/00 and/or with bottom temperatures consistently lower than 10-12°C. Colonies are also absent from areas of high silt deposition, although they may live on the edges of such areas. Positively, lunulites are known to occur in warm, shallow-shelf conditions, in temperatures of 10-29°C, on coarse, sandy to muddy sea-bottoms with low to 568 BULLETIN OF MARINE SCIENCE, VOL. 33, NO.3, 1983 moderate deposition, in fairly high velocity current regimes (70-100 em/sec), and in salinities ranging from 14-370/00. Depth distribution is strongly correlated with temperature and varies from 2.5 m (on wave-rippled sand) to 558 m in unusually warm, deep-water conditions (Lagaaij, 1963; Cullen, 1967; Maturo, 1968; Tom- masi et al., 1972; Buge, 1975; Cadee, 1975; Cook and Chimonides, 1978). Lunulite colonies are not large; the average sexually mature colony ranges from 6-12 mm in diameter, and maximum size is strongly correlated taxonomically. Some very large colonies (75 mm diameter) are known in a few Recent and fossil species, but others reach maturity when only 2-3 mm in diameter. Populations may be very large, and observations and estimates range from only 10, to 15,000 colonies per m2 (Marcus and Marcus, 1962; Cook, 1963; Greeley, 1967; Cadee, 1975). Faunas are usually taxonomically diverse, 4 to 6 different living species often occurring together, and as many as 9 to 16 forms being found in some fossil assemblages (Maplestone, 1904; Cook, 1965b; Maturo, 1968; Cadee, 1975). Among species, there are very strongly correlated sets of small, but highly significant differences of growth patterns, size at comparable growth stages, relative size and patterning of polymorphs, morphology of feeding zooids and avicularia, and zo- nation and structure of sexual zooids etc. In living populations these differences are also correlated with differences in the size and shape of opercula and mandibles, the number of tentacles, and the behavior and function of zooids in the different growth zones at comparable stages in colony life. Visceral, opercular and mandibular morphology is strongly reflected in skeletal structures, as is sexual polymorphism in some species. This allows fairly confident inferences as to the former behavior, population statistics and general biology of fossil populations (Cook, 1965a; 1965b; Hakansson, 1975; Chimonides and Cook, 1981). The regularity of colony growth and polymorphic patterning means that intracolony, microenvi- ronmental variation and change may be assessed (Boardman et al., 1969) and that fragments of colonies may be identified to species level in Recent and fossil assemblages (Lagaaij, 1953; Cook, 1965a). Larvae are brooded and are all assumed to be lecithotrophic. Some embryos are large (0.30-0.50 mm diameter), but free swimming life has been observed in very few forms. In one species, Cupuladria canariensis. where the embryo and larval diameter was 0.30 mm, swimming was observed to extend for 3 days before settlement (Cook, unpublished). Larger larvae may be inferred, by analogy with other bryozoans (Cook, 1968b; 1973; in press), to have a potential free swimming life of 5 days. Settlement and metamorphosis is usually upon a small sand grain, foraminiferan test or shell fragment 0.5 to 4.0 mm in diameter. There is some evidence that settlement on larger fragments may result in distorted growth or even non-development of the colony. In both shallow and deep-water free living sand fauna species, there is strong evidence that larvae are highly selective of the type, as well as the size of substratum (Lagaaij, 1963; Driscoll et al., 1971; Hayward and Cook, 1979). Some species develop with no substratum at all, but their larval life is unknown (Hakansson, 1975; 1981). The colony organization oflunulites is so integrated that fragments comprising two or three zooids only may regenerate to form a lunulitiform colony (Lagaaij, 1963; Cook, 1965a; Baluk and Radwanski, 1977). Fragmentation of colonies is known to occur when they are broken and predated by pagurid crabs (Greeley, 1967), and it is significant that many fossil and Recent populations are entirely composed of regenerated colonies. Other pagurids are known, however, merely to clean colonies of algae and bacterial film. In neither case does the association result in the death of colonies (Cook, in press). It is becoming increasingly evident COOK AND CHIMONIDES: HISTORY OF LUNULITE BRYOZOA 569

Figure I. Fossil and Recent Lunulites. A, L. plana d'Orbigny, Cretaceous, Villedieu, France (Group I) (XI2); B, L. bouei Lea, Eocene, Alabama, regenerated colony (XI9); C, L. capulus Busk, Recent, Australia (Group 2) (X22); 0, L. rutella Tenison Woods, Miocene, Australia, young colony with ancestrula (X25).

that a wide range of bryozoans provide a renewable food supply for a number of mobile predators and cleaners, some of which have an almost ectoparasitic relationship with their food source (Cook, in press). Some lunulite species also reproduce asexually by budding small, fan-shaped subcolonies peripherally, which later become detached and then bud differentially to form a lunulitiform shape (Marcus and Marcus, 1962). The structure of lunulite colonies is distinctive, but illustrates a remarkable convergence of two unrelated bryozoan families in adaptation to a free living sand fauna mode of life. There are strongly correlated sets of differing features between the two families, enabling any species from either group to be recognized and distinguished. The consistency of character correlations of visceral and mandibular structure with skeletal evidence allows these differences to be recognized in fragments and in fossil forms. Briefly, the differences may be summarized as follows. Colonies of Lunulitidae are budded from a single, founding ancestrular zooid (Fig. ID). Avicularian zooids are budded as interzooids and may be scattered (Fig. IA) or occur in radial series (Figs. IB, C). Processes for hingeing the mandible (condyles), may be simple and symmetrical (Figs. lA, B), or more complex, variously fused, and even spirally twisted (Fig. 2F). The avicularian frontal shield may be cuticular or calcified, forming an attachment for modified muscle systems (Fig. 2F). Generally, the simpler forms have paddle-shaped mandibles, whereas the complex forms have bristle-like mandibles (Cook, 1965a; Cook and Chi- 570 BULLETIN OF MARINE SCIENCE. VOL. 33. NO.3, 1983

Figure 2. Discoporel/a, Otionel/a and Selenaria. A, D. umbellata Defrance, Recent, South-east Africa (X48); B, Otionel/a sp. 3, Recent, New Zealand (avicularian condyles arrowed) (X31); C, O. perforata Canu and Bassler, Eocene, Mississippi (X48); D, S. auricularia Canu and Bassler, Eocene, Alabama (X22.5); E, S. magnipunctata Maplestone, Miocene, Australia (avicularian condyles arrowed) (X62); F, S. !enestrata Haswell, Recent, Australia (0 female, brooding zooids, m male zooids, a avicularia) (X58).

monides, 1978). The basal, colony-wide coelom is divided into radial compartments by cuticles which exactly parallel the overlying zooid rows. Each zooid communicates with its neighbors and with the basal coelom by means of large pores. Colonies ofCupuladriidae originate from a multizooidal, triadic ancestrular COOK AND CHIMONIDES: HISTORY OF LUNULITE BRYOZOA 571 complex. The avicularia are small and develop by differentiation from a common autozooid-avicularian bud, forming regular cormidia of one zooid and one distal avicularium throughout the colony. The radial basal coelomic compartments alternate with the overlying zooid rows, each of which communicates with its neighbors, one avicularium and two sectors of basal coelom (Cook, 1965a; HAk- ansson, 1973). Within each family of lunulites there is evidence for a mosaic of parallel and convergent changes in morphology with time. Present groupings of species are therefore of necessity arbitrary and are based upon broad degrees of overall similarity. There is a strong likelihood that they may not all reflect descendant sequences.

ORIGINS OF THE LUNULITE FAMILIES AND GENERA The Lunulitidae appear to be derived, almost certainly polyphyletically, from several closely related stocks of the Family Onychocellidae, which was widespread in Cretaceous times and includes genera with erect and encrusting growth forms. All known Onychocellidae possess large avicularia and Recent species have been observed to use these to clear deposits from the colony surface (Cook, in press). Bryozoans with normally encrusting, even massive, multilaminar colonies are known to develop analogues oflunulitiform colonies, by growing freely across the sediment from a minute substratum under sand fauna conditions (Cook, 1965c). Several Cretaceous stocks of Onychocellidae appear to have refined this capacity even further. This, together with an inferred preadaptive potential of their avicularian mandibular structure, was followed in Lunulites by the development of a basal coelom in Palaeocene forms. This seems to have resulted in the success of the fully integrated lunulite colony. The earliest known species, L. plana d'Orbigny (from the Santonian-Coniacian boundary of western France), has scattered, symmetrical avicularia (Fig. IA and Voigt, 1981, Fig. 2e). Some later species have scattered, asymmetrical avicularia. Other forms which became abundant in the European Camapanian have alternating radial rows of autozooids and symmetrical avicularia. These two groupings, each of which may include several parallel evolutionary sequences, are discussed here as Lunulites Group 1 and Group 2 respectively. Colonies with scattered, less numerous, unilaterally asymmetrical avicularia first appear in the North American Eocene together with Lunulites and may be descended from some Group I stocks. These form the Otionella group (Figs. 2B, C). The closely related Selenaria group also appears first in the North American Eocene and has even larger, less frequent avicularia (Fig. 2D). By Oligocene times, some Australian species of Selenaria possessed avicularia with calcified frontal shields and spiral condyle systems (Maplestone, 1904), which are also found in Recent forms (Fig. 2F). The origins ofthe Cupuladriidae are unknown. The earliest, Palaeocene species from West Africa was already highly integrated in colony structure, but Maas- trichtian deposits from the same area have not yielded any specimens (Gorodiski and Balavoine, 1961). The family probably includes three generic groups (Board- man et al., 1969), and the earliest Group, Cupuladria Group I, seems to be ancestral to both Cupuladria Group 2 and to Discoporella. The principal differences between these last two generic groups are the development of basal keno- zooidal systems within the colony-wide coelom in Cupuladria Group 2, and the presence of a calcified lamina beneath the frontal membrane of autozooids in Discoporella, neither of which features is present in Cupuladria Group I (Cook, 1965a; 1965b; HAkansson, 1973; Cadee, 1975). S72 BULLETIN OF MARINE SCIENCE, VOL. 33, NO.3, 1983

C Pa ~ll-¢- el20 •.O~ .S

E 0

~ll-¢- ,.0• el20 •.O~ .S(t .•.Clt:. 'YC2V' -q'~ +00

Figure 3. Distribution in time and space of records of Lunulites Groups I and 2, Otionella, Selenaria, Cupuladria Groups I and 2 and Discoporella. Many records are as yet unpublished and are based on numerous specimens from the Collections of the British Museum (Natural History), the National Museum of Victoria, the New Zealand Oceanographic Institute and the New Zealand Geological Survey. These include specimens from the Palaeocene (Lunulites, West Africa), the Eocene (Cupuladria, West Africa, Egypt, India) and the Oligocene (Lunulites, Otionella, Selenaria, Australia). A, Cretaceous and Palaeocene; B, Eocene and Oligocene.

Records of Lunulites in Time and Space The history of distribution of the Lunulitidae and Cupuladriidae is mapped in Figures 3 and 4. Only a small selection of localities can be shown at this scale, and in most cases records include several localities and species. More detailed surveys oflunulite distribution are numerous (Maturo, 1968; Lagaaij, 1952; 1953; 1963; Cook, 1965b; Tommasi et al., 1972; Buge, 1975; Cadee, 1975). Other works require taxonomic revision but indicate the abundance of records in some fossil deposits (Chapman and Crespin, 1928; Brown, 1952; Fleming, 1971). Post-Campanian spread of Group 2 Lunulites can be traced to the trans-Caspian region (Voigt, 1967), to Southern India (Stoliczka, 1872), Madagascar (Buge, 1951) and Timor (Bohm, 1924) by Late Cretaceous to Palaeocene times. Group I Cu- puladria and Groups 1 and 2 Lunulites were then also present in West Africa (Gorodiski and Balavoine, 1961). The abundant fauna of Groups 1and 2 Lunulites COOK AND CHIMONIDES: HISTORY OF LUNULITE BRYOZOA 573

M PI ""L1-¢- eL20 ¥O-\f- .Si) .C1L1. .•.C2\7 .00

P R ""11-¢- eL20 ¥-O-\f- .Si) .C1L1. "'C2\7 .00

Figure 4. Distribution in time and space of records of Lunulitidae and Cupuladriidae (see Fig. 3). Unpublished records include specimens from the Miocene (Cupuladria, Canary Islands, Discoporella. Indonesia and Olianella. Australia) and Recent (Olianella. Australia and Selenaria. New Zealand). A, Miocene and Pliocene; B, Pleistocene and Recent. found in the Gulf of Mexico region during the Eocene and Oligocene (Canu and Bassler, 1920; 1923) seems to be derived from Brazilian Palaeocene populations (Buge and Muniz, 1974). Both forms of Lunulites remained common in Europe during the Eocene and Oligocene and were joined by a spreading and diversifying fauna of Cupuladriidae (Malecki, 1963; Buge and Debourle, 1971). Cupuladria also reached Egypt and northern India during Eocene times. The first, Eocene records of Otionella in North America were followed by Oligocene species in New Zealand (Fleming, 1971) and in Australia. Selenaria has a similar American history, but first appears in the Australian Oligocene only. Lunulites, Otionella and Selenaria coexisted with all genera of Cupuladriidae in the South American Miocene (Canu, 1904; Buge and Muniz, 1974), as did Lunulites and the Cupu- ladriidae in Europe and West Africa (Buge and Carvalho, 1964; Buge, 1973; Cadee, 1977). In the Gulf region, all Lunulitidae became extinct at the end of the Oli- gocene, and were later replaced by Cupuladriidae during the Miocene (Lagaaij, 1963), when Discoporella was also present in Chile (Philippi, 1887). Scattered Miocene records of Group 1 Cupuladria and of Discoporella occur in the Indo- Pacific region, and Cupuladria seems to have reached Australia by mid-Miocene 574 BULLETIN OF MARINE SCIENCE, VOL. 33, NO.3, 1983 times. The New Zealand fauna of Otionella, and the Australian fauna of Lunulites, Otionella and Selena ria reached a peak of abundance and diversity in the Miocene (MacGillivray, 1895; Maplestone, 1904; Brown, 1952), which has continued with little change to the present day. In South America, West Africa and Europe, all Lunu/ites became extinct by the Pleistocene, and the Recent distribution of circum-tropical and subtropical Cupuladriidae and Australasian Lunulitidae became established.

Inferred Historical Biogeography of the Lunulites Given the records summarized above, what may be concluded or inferred about the history of dispersal and restriction of the lunulites? First, it is important to distinguish between real absences and lack of records, and to establish when and where real absences occurred. This includes absences of both lunulite families from areas which could have supported them, as well as absences of one family only, because both are known to coexist. The European Cretaceous to Recent has been well studied; therefore the absence of alliunulites before the Santonian, of Cupuladriidae before the Eocene, and the total absence of Otionella and Selenaria are almost certainly all real. The late Cretaceous faunas of North America have also been studied in some detail, and the absence of Lunulitidae has been particularly noted (Shaw, 1967). Other forms ofOnychocellidae (such as the genera Coscinopleura and Cheethamia), which are found with European Lunu/ites, are present in the North American deposits, but always appear later in the stratigraphic column than their European equivalents. The extinction of the Lunulitidae at the end of the North American Oligocene has been documented in detail (Lagaaij, 1963). In all other areas, gaps in the fossil record, or total lack of investigation (Moyano, 1982), even though the deposits are principally composed of bryozoan remains (Brown, 1952), makes it difficult to establish real absences. With these provisos in mind, it is still possible to review the evidence for dispersal of the lunulites and the evidence for fragmentation and isolation of pre-existing faunas by the occurrence of barriers to dispersal and exchange caused by plate movements and temperature and salinity changes in time and space. The known environmental parameters controlling lunulite distribution may also be used to test the feasibility of routes and rates of dispersal of some lunulite stocks. Dispersal of a shallow-shelf marine animal, which however free living, or even capable of limited locomotion, is essentially sessile (see above), must normally be by means of a motile larval stage. Successful settlement and metamorphosis after random or current-borne dispersal depends only upon suitable substrata being available in areas within the other environmental tolerances of the species concerned. Although some lunulite larvae are large, they are all assumed to be lecithotrophic, and a prolonged planktonic life of weeks or months is not feasible. Lunulites are also specific in choice of minute bottom sediment particles as substrata for settlement, and dispersal by 'rafting' on algae etc. is not a feasible explanation of their wide distribution, as it is for many other bryozoans (Ekman, 1967; Lagaaij and Cook, 1973). As the temperature tolerances of lunulites have a minimum level of 10°C, dispersal of successive generations across abyssal sea bottoms is also not a feasible explanation. Inferring a minimal, annual breeding season, dispersal of successive generations of Lunulites larvae along the shelfwaters of Late Cretaceous to Palaeocene Tethys, to Timor and even to Australia presents few problems in interpretation. Although lunulites are most abundant in large, sandy areas, any small patch of sand even COOK AND CHIMONIDES: HISTORY OF LUNULITE BRYOZOA 575 less than 1 m2 can support quite a large population. The overall oceanic current of Tethys has been inferred to be westerly in direction (Haq, 1981), but presumably inshore counter-currents existed. Dispersal of Palaeocene Lunu/ites to West Af- rica, and of Eocene Cupuladria to Europe and Australia is inferred to have occurred in a similar manner along the Tethyan and eastern Atlantic seaboard. Given 5 million years for such dispersal, a rate of only 3-4 m per generation is necessary. The crossing of the Atlantic Ocean, even in Late Cretaceous to Palaeocene times, when the distance from West Africa to Brazil may be inferred to have be,en approximately 800-1,000 km, presents different problems in interpretation. Al- though the higher temperatures of the Early Tertiary seas (Haq, 1981) would allow a theoretical lowering of the 10°C isotherm to a depth of 500-600 m, this would still not have enabled West African Lunu/ites stocks to have reached Brazil by abyssal radiation, and current-borne larval dispersal must be invoked. The inferred current pattern of the Palaeocene Atlantic includes a north-westerly equatorial flow from West Africa to South America (Berggren and Hollister, 1974; Haq, 1981). Generally, oceanic currents have a low velocity (10-45 em/sec, Ek- man, 1967), although subsurface jet-streams with a velocity of 120 em/sec are known (McCreary, 1981). The narrowness of the Palaeocene Atlantic allows com- parison with other oceanic boundary current systems which are close to continental masses. The Florida, Alguhas and Kuroshio Currents, for example, all extend for several hundred kilometers, at velocities of 180-190 em/sec, and affect the shelf waters to a depth of 200 m (Ekman, 1967; Takenouti, 1972). Currents like these would affect bottom living larvae, and given a free swimming life of 3-5 days could transport them 500-800 km before settlement. Although Palaeocene Lu- nu/ites could therefore have crossed the Atlantic by direct larval dispersal, the Miocene dispersal of Cupuladriidae would have required several intermediate areas of settlement in order to cross the ocean, which by then was at least 2,000 km wide. The presence of sea-mounts and small islands, some of which, like Fernando do Noronha, are very ancient (120 my) allow an alternative, earlier date for dispersal of the Cupuladriidae. Although the present depth of several sea- mount areas is below the inferred 500-600-m limit of the Tertiary 10°C isotherm, it may be postulated that in the Eocene to Oligocene they were both larger in extent, and nearer the surface than today. As all sea-mounts and islands may be inferred to have originated from the mid-Atlantic Ridge, they were also much closer to their point of origin and to each other in the early Tertiary. As Eocene West African and European populations of Cupuladriidae were already well di- versified, it is possible that sea-mount areas on either side of the mid-Atlantic ridge already possessed a fauna before increasing distance and decreasing current velocity made further recruitment occur with diminishing success. The increasing abundance of these intermediate populations would have made dispersal to the South American shelf a statistical certainty by the Late Oligocene. Although none of these areas has as yet been investigated for evidence of fossil Cupuladriidae, the close similarity of the western and eastern Atlantic faunas, and the rapid spread ofCupuladriidae in the Miocene of the Gulfregion could thus be explained. This rapid appearance of large and diverse populations is mirrored in Europe, where records are sparse in the Eocene and Oligocene, but become abundant in the Miocene (Cadee, 1979). Today, there are isolated faunas of Cupuladriidae in the Azores and the Galapagos (Cook, 1965b), each more than 1,000 km from the nearest land mass, and surrounded by deep water and slow moving current systems (Wooster and Reid, 1963). These too, are probably relics of more extensive faunas which inhabited intermediate areas produced by volcanic activity. The close similarity of Early Eocene Otionella and Selenaria from the Gulf 576 BULLETIN OF MARINE SCIENCE, VOL. 33, NO.3, 1983 region (Canu and Bassler, 1920; 1923) with some South American Miocene forms (Canu, 1904) and Oligocene to Miocene Australian species (MacGillivray, 1895; Maplestone, 1904), together with the real absence of these genera from the Tethyan region, suggests that they are isolated elements of a once extensive, early Tertiary southern fauna. Evidence for a widely dispersed southern fauna of Foraminifera and Mollusca in the Maastrichtian and Palaeocene (Webb, 1973; Fleming, 1979) suggests a homogeneity of environment which may have continued through the Palaeocene and Eocene. Dispersal of stocks of Otionella and Selenaria could not have occurred before the Eocene, and however fragmented a fauna may become, some of its original stocks have first to radiate over a major part of its maximum range. During the Eocene, sea temperatures have been estimated as being at least 10°C higher than at present, allowing a minimum level of 10°C round the Antarctic shelf. The relatively late separation of South America from Antarctica in the Early Oligocene (Barron et al., 1978; Haq, 1981) suggests that two possible routes of Eocene dispersal from the Gulf region may be postulated. Given 5 million years, stocks of Otionella and Selena ria could have reached New Zealand and South- East Australia via the eastern Pacific shelf of South America and westward along the Antarctic shelf (approximately 15,000 km), or via the west Atlantic shelf of South America and eastward along the Antarctic shelf (approximately 17,000 km), at a rate of 3-4 m per generation, This is similar to the rate postulated for the Tethyan dispersal of European Lunu/ites stocks to Australasia. The Eocene separation of Australia from Antarctica was accompanied by high velocity, probably easterly currents (Kennett and Watkins, 1973) which may have enabled stocks of Otionella to reach New Zealand from the west. However, New Zealand was already fairly distant from the Australian-Antarctic shelf by Eocene times (Grif- fiths, 1973), and an earlier dispersal from the east, via the Auckland and Cambell Plateau, is just as feasible. To a certain extent, the distribution of Otionella and Selenaria from the Oligocene (Bock and Gilenie, 1965; Fleming, 1971) of Australia and New Zealand suggests a dual origin of the fauna. Although several species of Otionella occur in the Tertiary to Recent of Australia, only one species of Selenaria occurs in New Zealand, and this has no fossil record there. The sea-mounts and islands now present between Australia and New Zealand are Late Tertiary in origin (Griffiths and Varne, 1972), and may have enabled this later dispersal to take place. It is also significant that no species of Lunu/ites or of Cupuladria has ever been reported from New Zealand (Table I). During the Late Oligocene, the establishment of a circum-Antarctic current, glaciation and a catastrophic fall in sea temperatures is inferred to have isolated the Miocene 'lunulite' faunas of South America and Australia, and to have caused the extinction of the intervening Antarctic shelffauna (Haq, 1981). The apparently dramatic extinction of the Lunulitidae in North America and the Gulf region cannot be explained in terms of temperature deterioration (Ekman, 1967), which was less severe than in Europe, where mixed populations of Lunu/ites and Cu- puladriidae survived (Lagaaij, 1953; Buge, 1973; Cadee, 1977). The presence of clay beds above some of the Oligocene deposits in which the Lunulitidae were preserved is similar to that which also inhibited occurrence of Miocene Cupu- ladriidae in the western Gulf (Lagaaij, 1963). This suggests that an increase in very fine sedimentation may have been one contributory factor in the extinction of the Lunulitidae in this area. At the end of the Miocene, increased salinities and the closure of western central Tethys effectively isolated the Atlantic and Indo-Pacific faunas of Cupuladriidae. This is reflected in the nature of the populations found with Otionella and Selenaria in South America and Australia respectively. The South American Miocene species belong to Cupuladria Group COOK AND CHIMONlDES: HISTORY OF LUNULITE BRYOZOA 577

Table I. Distribution of some lunulite species in the Tertiary to Recent of Australia and of New Zealand

Australia New Zealand Recent Lunulites capulus Otionella squamosa Lunulites repandus Otionella sp. 1 Otionella squamosa Otionella sp. 2 Otionella nitida Otionella sp. 3 Otionella sp. 3 Otionella sp. 4 Selena ria spiralis Selena ria sp. 1 Selena ria alala Selenaria sp. 1 Cupuladria guineensis Pleistocene-Pliocene Lunulites capulus Otionella squamosa Lunulites cupola Otionella sp. 1 Selenaria spiralis Otionella sp. 3 Otionella sp. 4 Upper and Mid-Miocene Lunulites capulus Otionella sp. 2 Lunulites cupola Otionella sp. 3 Selena ria alala Selena ria otwayensis Cupuladria sp. I Lower Miocene Lunulites cupola Otionella sp. 2 Otionella sp. 2 Otionella sp. 3 Selena ria spira lis Otionella sp. 5 Selena ria alala Selena ria otwayensis Upper Oligocene Lunu/ites cupola Otionella sp. 3 Selena ria spira/is Otionella sp. 5 Selena ria otwayensis

2 and to Discoporella, and are part of a diverse Atlantic fauna which includes at least 10 species-complexes (Cadee, 1975; 1977; 1979). The Australian Miocene species is closely similar to the single, Group 1 species-complex found today in the same region (Cook, 1965b). The Miocene lunulite faunas of both regions may therefore be regarded as being composed of relics of the Early Tertiary southern fauna, plus newly arrived Cupuladriidae from the North, which could no longer disperse along the Antarctic shelf.

Australasian Late Tertiary to Recent Biogeography Although the present distribution of the Lunulitidae and Cupuladriidae shows an overwhelming bias in favor of the younger group (Fig. 4), there is no evidence that the Cupuladriidae have ever replaced the Lunulitidae by successful compe- tition. The Late Tertiary to Recent faunas of lunulites in the Pacific may be summarized as follows. First, there is a relic population of Gulfian species of Cupuladriidae in California, west Mexico and the Galapagos. Second, there is an Indo-West Pacific fauna of Cupuladriidae derived from Early Tertiary Tethyan stocks. Third, there is a large Australian fauna of Lunulites, which has declined in diversity, but not in abundance since the Miocene. Some of these forms may be derived from Palaeocene stocks from eastern Tethys. Fourth, there is a large, complex and diverse fauna of Australasian Otionella and Selenaria, which was probably derived and isolated from an Eocene circum-Antarctic fauna. The present distribution of Australasian lunulites is extensive. Two species of Lunulites occur in southern Australia, one of which also occurs in the Torres 578 BULLETIN OF MARINE SCIENCE, VOL. 33, NO.3, 1983

Straits, showing a wide temperature tolerance. Although Otionella is principally distributed in New Zealand, where 6 species have been recognized, 6 further species, the majority undescribed, also occur off the Australian coasts. In addition, 13 species of Selena ria, one of which also occurs in New Zealand, have been found, often together, from Australian waters. The single species of Indo-West Pacific Cupuladria has a wide range, extending from the Philippines to the Bass Straits.

DISCUSSION In spite of the large amount of information available, the presently known and inferred history of the lunulites poses many questions. Much further work is required before a more complete history may be written. First, investigations of changes in structures with time, such as the evolution of basal coeloms and complex avicularia, are needed in order to understand the systematics of both families. Second, more studies on inferred and observed reproductive biology, both sexual and asexual, are needed on fossil and Recent assemblages, in order to understand infant mortality and population structure (Hakansson, 1975; 1981). Above all, more work is required on living lunulites, including observations of larval life, settlement behavior and substratum preferences, the function of lo- comotory potential and its relationship with sexual polymorphism, and the par- tition of food resources among populations which have a high density and diversity, together with a wide range in colony size. Because colonies are small but highly integrated it is easy to regard each as a single animal. The concepts of coloniality are therefore easier to grasp and analyze in lunulites than in larger, or more amorphous colony forms (Rosen, 1979). Study of the nervous communication and physiology, together with investigation of colony-wide behavior patterns oflunulites, could therefore contribute to the study of coloniality in general. Known records need to be re-examined, and further information is required on the stratigraphic distribution of many species, particularly from the relatively uninvestigated West African, Indonesian and South American regions. A search also needs to be made for real evidence of the postulated intermediate Atlantic populations, and of the postulated southern fauna in the Antarctic, even though few deposits may remain after tectonic disturbance and late Oligocene glaciation (Webb, 1981). Although living faunas ofCupuladriidae are abundant in West Africa, the Gulf of Mexico and the Atlantic coasts of South America, coexistent faunas of Lu- nulitidae and Cupuladriidae can only be found today in Australia. Whether or not these are all descendants of the forms which were equally abundant in the Cretaceous to Palaeocene seas of West Africa and Europe, and the Eocene seas of Central America, part, at least of the living Australasian fauna had its origins in areas and times remote from its present distribution. Discovery of how and when these stocks arrived in Australia, and how and when they became isolated there is part of the historical biogeography of the South Pacific. The distinctive and restrictive ecological parameters controlling the existence and dispersal of lunulite species also means that they have considerable potential in interpretation of past environments in many other regions of the world. Apart from massive pollution, the greatest threat to these animals is probably that of over-collection, in spite of their local abundance. Their palaeoecological and palaeobiogeograph- ical significance makes it important, however, to continue study of living species of these now uniquely Australasian animals. COOK AND CHIMONIDES: HISTORY OF LUNULITE BRYOZOA 579

ACKNOWLEDGMENTS

Many colleagues have contributed to this paper, and we can mention only a few here. We are particularly grateful to Drs. P. Arnold (James Cook University of Northern Queensland), G. C. Cadee (Netherlands Institute for Sea Research), D. P. Gordon and P. K. Probert (New Zealand oceanograph- ical Institute), P. E. Bock (Royal Melbourne Institute of Technology), E. Hilkansson (Geological Institute, Copenhagen University), R. E. Wass (Department of Geology and Geophysics, University of Sydney), H. I. Moyano (University of Concepcion, Chile) and P. D. Taylor (British Museum, Natural History), for all their help and interest.

LITERATURE CiTED

Baluk, N. and A. Radwanski. 1977. The colony regeneration and life habitat offrce living bryozoans. Acta Geol. Pol. 27: 143-156. Barron, E. J., C. G. A. Harrison and W. W. Hay. 1978. A rcvised rcconstruction of the southern continents. Eos 59: 436-449. Berggren, W. A. and C. D. Hollister. 1974. Paleogeography, paleoceanography and the history of the circulation in the Atlantic Ocean. Pages 126-186 in W. W. Hay, ed. Studies in paleoceanography. Soc. Econ. Paleont. Min. Spcc. Pub I. 20. Boardman, R. S., A. H. Cheetham and P. L. Cook. 1969. Intracolony variation and the genus concept in Bryozoa. Proc. N. Am. Paleont. Conv. 1969 pt. C: 294-320. Bock, P. E. and R. C. Gilenie. 1965. Late Cretaceous and Tertiary depositional cycles in southwestern Victoria. Proc. R. Soc. Vict. 79: 153-163. Bohm, J. 1924. Ueber eine senone Faune von Misol. Palaeont. Timor 14(24): 83-10 1. Brown, D. A. 1952. The Tertiary Cheilostomatous Polyzoa of New Zealand. British Museum (Natural History), London. 405 pp. Buge, E. 1951. Bryozoaires. Pages 87-88 in M. Collignon, ed. Le Cretace superieur d'Antonibe. Couches de passage du Cretace au Tertiare. Ann. Geol. Servo Min. Madagascar 19. --. 1973. Les Bryozoaires Miocenes du Nord-Ouest dc l'Aliemagne. Paleont. Z. 47: 32-53. --. 1975. Distribution des bryozoaires lunulitiformes sur les cotes du Brezil. Docums Lab. Geol. Fac. Sci. Lyon H. S. 3: 439-448. -- and A. M. G. Carvalho. 1964. Sobra a presenca de Bryozoarios no miocenico de Angola e de Mo;;ambique. Garcia de Orta 12: 421-426. --- and A. Debourle. 1971. Presence dans Ie Bartonien d' Aquitaine occidentale de Cupuladria boulangeri n. sp. (Bryozoa, Cheilostome). Bull. Cent. Rech. Pau 5: 35-47. --- and G. da C. B. Muniz. 1974. Lunuliles (Heleraclis) barbosae- nou velie espece de bryozoaires lunulitiformes (Bryozoa, Cheilostomata) du Paleocene du Nord-Est du Brezil. Annis. Paleont. Invert. 60: 191-201. Cadee, G. C. 1975. Lunulitiform bryozoa from the Guyana shelf. Neth. J. Sea Res. 9: 320-343. ---. 1977. Bryozoa from the Late Miocene Mica Clay of Morsum Kliff, Sylt, Western Germany. Meded. Werkgr. Tert. Kwart. Geol. 14: 43-50. ---. 1979. Thc Cupuladria canariensis complex. Pages 443-459 in G. P. Larwood and M. B. Abbott, eds. Advances in bryozoology. Academic Press, London and New York. Canu, F. 1904. Les Bryozoaires du Patagonien. Mem. Soc. Geol. Fr. 12(3): 1-30. --- and R. S. Bassler. 1920. North American Early Tertiary Bryozoa. Bull. U.S. Natn. Mus. 106: 1-879. --- and ---. 1923. North American Later Tertiary and Quaternary Bryozoa. Bull. U.S. Natn. Mus. 125: 1-302. Chapman, F. and I. Crespin. 1928. The Sorrento Bore, Mornington Peninsula, with a description of new or little-known fossils. Rec. Geol. Surv. Vict. 5: 1-195. Chimonides, P. J. and P. L. Cook. 1981. Observations on living colonies of Selenaria (Bryozoa, Cheilostomata) II. Cah. BioI. Mar. 22: 207-219. Cook, P. L. 1963. Observations on live lunulitiform zoaria of Polyzoa. Cah. BioI. Mar. 4: 407-413. --. 1965a. Notes on the Cupuladriidae (Polyzoa, Anasca). Bull. Br. Mus. Nat. Hist. Zool. 13: 151-187. ---. 1965b. Polyzoa from West Africa. The Cupuladriidae (Cheilostomata, Anasca). Bull. Br. Mus. Nat. Hist. Zool. 13: 189-227. ---. 1965c. Notes on some Polyzoa with conical zoaria. Cah. BioI. Mar. 6: 435-454. ---. 1968a. Bryozoa (Polyzoa) from the coasts of tropical West Africa. Atlantide Rep. 10: 115- 262. --. 1968b. Observations on living Bryozoa. Ani. Soc. Ital. Sci. Nat. 108: 155-160. ---. 1973. Settlement and early colony development in some Cheilostomata. Pages 65-71 ill G. P. Larwood, ed. Living and fossil Bryozoa. Academic Press, London and New York. 580 BULLETIN OF MARINE SCIENCE. VOL. 33. NO.3. 1983

---. 1979a. Some problems in interpretation ofheteromorphy and colonia] integration in Bryozoa. Pages 193-210 in G. P. Larwood and B. R. Rosen, eds. Biology and systcmatics of colonial organisms. Academic Press, London and New York. --. 1979b. Mode oflife of small, rooted 'sand fauna' colonies of Bryozoa. Pages 269-282 in G. P. Larwood and M. B. Abbott, eds. Advances in bryozoology. Academic Press, London and New York. --. 1981. The potentia] of minute bryozoan colonies in the analysis of deep sea sediments. Cah. BioI. Mar. 22: 89-106. --. In Press. Bryozoa from Ghana-a preliminary survey. Annis. Mus. R. Afr. Cent. 8. No. 235, Zool. --- and P. J. Chimonides. 1978. Observations on living colonies of Selena ria (Bryozoa, Chei- lostomata) 1. Cah. BioI. Mar. 19: 147-]58. --- and ---. 1981. Morphology and systematics of some rooted cheilostome Bryozoa. J. Nat. Hist. 15: 97-134. --- and R. Lagaaij. 1976. Some Tertiary and Recent conescharclliniform Bryozoa. Bull. Br. Mus. Nat. Hist. Zool. 29: 317-376. Cullen, D. J. 1967. The submarine geology of the Foveaux Strait. Bull. N.Z. Dep. Scient. Ind. Res. 184: 5-67. Driscoll, E. c., J. W. Gibson and S. W. Mitchell. 1971. Larval selection of substrate by the Bryozoan Discoporella and Cupuladria. Hydrobiologia 37: 347-359. Ekman, S. 1967. Zoogeography of the sea. Sidgwick and Jackson, London. 415 pp. Flcming, C. A. 1971. New Zealand Bryozoa. Catalogue of specimens in thc N .Z. Geological Survey. Rep. Geol. Surv. N.Z. 50: 1-43. ---. 1979. Evolution of the South Pacific marine biota: the expanding fossil record. Pages 5-26 in D. Montgomery, ed. Proceedings of the International Symposium on Marine Biogeography and Evolution in the Southern Hemisphere. N.Z.D.S.1.R. Inform. Ser. 137, Vol. I, Auckland, New Zealand. Gorodiski, A. and P. Balavoine. 1961. Bryozoaires cretac(~set eoccnes du Senegal. Bull. Bur. Rech. Geol. Min. Paris 4: 1-15. Greeley, R. 1967. Natural orientation of lunulitiform bryozoans. Bull. Geol. Soc. Am. 78: I] 79- 1182. Griffiths, 1. R. 1973. Plate tectonics and the evolution of New Zealand. Pages 263-269 in R. Fraser, ed. Oceanography of the South Pacific. N.Z. National Commission for U.N.E.S.C.O. Wellington, New Zealand. --- and R. Varne. 1972. Evolution of the Tasman Sea, Macquarie Ridge and Alpine Fault. Nature 235: 83-86. Hflkansson, E. 1973. Mode of growth of the Cupuladriidae (Bryozoa, Cheilostomata). Pages 287- 298 in G. P. Larwood, ed. Living and fossil Bryozoa. Academic Press, London and New York. ---. 1975. Population structure of colonial animals: a palaeoecological study of some free-living, Cretaceous Bryozoa. Docums Lab. Geol. Fac. Sci. Lyon H. S. 3(2): 385-399. ---. 1981. Breeding, brooding and 'parental care' in Recent Lunulites. Page 312 (abstract) in G. P. Larwood and C. Nielsen, eds. Recent and fossil Bryozoa. Olsen and Olsen, Fredensborg. Haq, B. U. 1981. Paleogene paleoceanography: early Cenozoic oceans revisited. Oceanologica Acta No. SP: 71-82. Hayward, P. J. and P. L. Cook. 1979. The South African Museum's Meiring Naude Cruises, Part 9, Bryozoa. Ann. S. Afr. Mus. 79: 43-130. --- and ---. 1983. The South African Museum's Meiring Naude Cruises, Part 13, Bryozoa. Ann. S. Afr. Mus. 91: 1-158. --- and 1. S. Ryland. 1979. British Ascophoran Bryozoans. Synopses of the British Fauna No. 14. Linnean Society of London. Academic Press, London and New York. Humphries, C. J. 1981. Biogeographical methods and the southern beeches. Chap. 21, pages 283- 297 in P. L. Forey, ed. The evolving biosphere. British Museum (Natural History), Cambridge University Press. Kennett, J. P. and N. D. Watkins. 1973. Evidence for a major change in deep-water circulation during the Plio-Pleistocene in the south-west Pacific. Page 173 in R. Fraser, ed. Oceanography of the South Pacific. N.Z. National Commission for U.N.E.S.C.O. Wellington, New Zealand. Lagaaij, R. 1952. The Pliocenc Bryozoa of the Low Countries. Meded. Geol. Sticht. C5(5): 1-233. ---. 1953. The vertical distribution of the lunulitiform Bryozoa in the Tertiary of the Netherlands. Meded. Geol. Stichl. 7: 13-19. --. 1963. Cupuladria canariensis (Busk)-portrait of a bryozoan. Palaeontology 6: ]72-217. -- and P. L. Cook. 1973. Some Tertiary to Recent Bryozoa. Pages 489-498 in A. Hallam, ed. Atlas of palaeobiogeography. Elsevier Scientific Publishing Company, Amsterdam and London. COOKANDCHIMONIDES:HISTORYOFLUNULITEBRYOZOA 581

MacGillivray, P. H. 1895. A Monograph of the Tertiary Polyzoa of Victoria. Trans. R. Soc. Vict. 4: 1-166. Malecki, J. 1963. Bryozoa from the Eocene of the Central Carpathians between Grybow and Dukla (in Polish). Pr. Geo!. 16: 7-158. Map]estone, C. M. 1904. Notes on the Victorian fossil Selenariidae and descriptions of some new species (Recent and fossil). Proc. R. Soc. Viet. 16: 207-217. Marcus, E. and E. Marcus. 1962. On some lunulitiform Bryozoa. Bolm Fac. Filos. Cien~. S. Paulo, Zoo!. 24: 281-342. Maturo, F. J. S. 1968. The distributional patterns of the Bryozoa of the east coast of the Unitcd States exclusive of New England. Atti. Soc. Ital. Sci. Nat. 108: 261-284. McCreary, J. ]981. A linear stratified ocean mode] of the equatorial undercurrent. Phil. Trans. R. Soc. Lond. 298(1 ]44): 603-635. Moyano, H. I. 1982. Magellanic Bryozoa: some ecological and zoogeographical aspects. Marine Biology Berlin 67: 81-96. Philippi, R. A. 1887. Die Tertiiiren und quartiiren Versteinerungen Chiles. Leipzig. 226 pp. Rosen, B. R. 1979. Modules, members and communes. Pages xiii-xxxv in G. P. Larwood and B. R. Rosen, eds. Biology and systematics of colonial organisms. Academic Press, London and New York. Ryland, J. S. and P. 1. Hayward. 1977. British Anascan Bryozoans. Synopses of the British Fauna No. 10. Linnean Society of London. Academic Press, London and New York. Shaw, N. G. 1967. Cheilostomata from Gulfian (Upper Cretaceous) rocks of southwestern Arkansas. J. Paleont. 4]: 1393-1432. Stoliczka, F. ]872. The Cretaceous fauna of southern India. The Ciliopoda. Mem. Geol. Surv. India Palaeont. Indica 4: 33-68. Takenouti, Y. 1972. Preview on the contribution of CSK to the physical oceanography of the Kuroshio. Pages 11-] 9 in K. Sugawara, ed. The Kuroshio II. Proc. second CSK symposium. Tokyo. Tommasi, L. R., A. C. Marini and C. F. A. Rosa. 1972. Briozoarios lunulitiformes da regiao de Jeha Grande (RJ). Bolm Inst. Oceanogr. S. Paulo 21: 137-]47. Voigt, E. 1967. Oberkreide-Bryozoen aus den asiatischen Gebieten der UdSSR. Mitt. Geo!. Stlnst. Hamb. 36: 5-95. ---. 1981. Repartition et utilisation stratigraphique des Bryozoaires du Cretace Moyen (Aptien- Coniacien). Cretaceous Research 2: 439-462. Webb, P. N. 1973. Preliminary comments on Maastrichtian-Paleocene Foraminifera from Lord Howe Rise, Tasman Sea. Pages 321-324 in R. Fraser, ed. Oceanography of the South Pacific. N.Z. National Commission for U.N.E.S.C.O. Wellington, New Zealand. ---. 1981. Late Mezozoic--Cenozoic geology of the Ross Sector, Antarctica. J. R. Soc. N.Z. II: 439-446. Wooster, W. S. and J. L. Reid. 1963. Eastern boundary currents. Chap. 11, pages 253-280 in M. N. Hill, ed. The Sea. Vol. 2. Interscience Publishers, New York and London.

DATEACCEPTED: January 19, 1983.

ADDRESS:Department o/Zoology, British Museum (Natural History). Cromwell Road. London SW7 5BD, u.K.