127.

MARINE MOLLUSCS

OF MAYOR ISLAND

E.N. Mllligan.

Most of the collecting was from open rock and sheltered reef habitats (large stones and boulders). Although sandy beaches were present at Opo, Omapu and Orira (N.W.Bay), they appeared to be too steep for colonization by sand flat molluscs. Some sublittoral species which encroach into the tidal zone on sand flats were found Yi/ashed up on the beach, e.g. Barysplra spp. Omapu Bay was more exposed than Opo, and in • the former a good deal of sand occurred with the stones where collect• ing was done. Opo Bay supplied more typical sheltered reef condit• ions with large immovable rock blocks rising from below extreme low tide, and with smaller stones amongst them which at low tide were generally free from sand, Collecting was not primarily for compiling a species list. Doubtless a few common species widespread in dist• ribution were not collected or recorded for inclusion, e.g. Melag- raphia, Nerita9 Siphonaria. Eighty species were recorded, - the number being increased by 14 specimens, in drift. Some are from shallow water, but others are deep water or pelagic, These latter two are characteristic of exposed coasts and islands where the land shelves deeply off-shore. Besides these there is the record of 4 Cephalopods, 3 of which are rather rare on our coasts, ' Spirula spirula, the common white ram's horn•shell, has been found to live in depths between 110 fathoms to 1,100 fathoms. One, specimen of Tethys tryoni was found washed up but none were•found in pools. This evidently was not the season for these annual tectibranchs to come into shallow water to breed. The specimen found was purplish and not the brown colour of specimens found in pools. The purplish colour appears to be characteristic of this mollusc- during its off• shore phase. Of interest also were two species, Notosinister in- felix and Joculator dirempus9 originally found alive only by dredging, which were found living in Microdictyon in a deep high-tidal pool* Washings from this algae produced the large number of 24 species. In the following lists numbers 'following the species are those- in the check lists of Powell (1946 and 1.953). Saxostrea is a synonym of Crassostrea (Thomson ~ 1954).

+ Denotes found on more than one of the' islands.

* Denotes found on all three. 128.

PELECYPODA Philobryidae: +Hochstetteria munita 43-1 spec., high tide pool, Opo. Cosa filholi 48-1 spec., in drift, Opo Bay. Mytilidae: - " »Trichomusjculus barbatus 68—low tide crevices,-Opo, Omapu, Ostreidae: -.- *Crass6strea glomerata 100.-more sheltered rock shelves, "': ":A^-i-Opo Bay. Carditidae: +Cardita- aoteana 1,29- - 1 juvenile valve,'.drift,.- Opo. Leptonidae: +Lasāea maoria 1 66 .-' high tide-muddy crevices., N. arm, Opo. +L. hi nemo a i 67 -• dead shells,. drift, Opo. .ii.-. +Notolepton sanguineum 197 - ditto.. +N. citrihum 198 - Ditto. Veneridae: —...vv +Tawera spissa 251 - dead shells, drift, Opo. Chione (Austrovenus) stutchburyi 2!i>7 - ditto. Hiatellidae: •fHiatella australis 273 - common in low tide crevices and • under stones, Opo.

< G A S T> E- R 0 P 0 D A

Scissurellidae: +Scissurona rosea 305 - common, high tide pools, Opo.

Haliotiidae: t ' ' *Haliotis (Paua) iris 313 - common on rocks, S.Opo Bay. ^:

r -; Incisura lytteltonensis 318 - common, low tide seaweed • washings, Omapu Bay;.high tide pool, Opo. ^Tugali suteri bascauda. 325 common under-; low tide rocks, Opo Bay. r , Trochidae.: •'' •••-V:-'••' ^^"''^'^;-:^--'• . r, , ;' »Thoristella oppressa- 346 - -common on low tide' seaweed/ '.. : Opo and Omapu.; : ,- .., ' ": Paraclanculus peccatus 349 - 1 spec, of this rare mollusc found in seaweed drift, Omapu, by E.l/hite. *Anisodiloma lugubrls 360..- low tide "under smooth stones,Opo. Cantharidus purpuratus 364 - 1 spec. , Opo drift. (pu. Micrelenchus tenebrosus 373 - 2 spec.-, low tide stones,0ma- *M. dilatatus 377 - common on low tide seaweed, Opo. 129.

Cantharidella tesselata 379 - common on low tide seaweed,Opo. +Fossarina rimata 380 - few specimens in high tide crevices, North Opo. Stomatellidae: -'"Herpetapoma bella 381- - common under stones, low tide, Opo. Liotiidae: -*"Liotella polypleura 429 - common, high tide pool, Opo. Turbinidae: '•'Lunella smaragda 488 - common on stones & weed, low tide,Opo. Patelloididae: »Notoacmea pileopsis 509 - abundant, high tide, exposed rock. +N. pileopsis cellanoides 51 9 - not common as last but on rough surfaces or head of washes. N. subtllis 514 - 1 spec, of this deepwater sp., drift, Opo. *Atalacmea fragilis 521 - common under smooth stones, Opo. Patellidae: ^Cellana radians 523 - common on rock raid-low tide. Wide variation in this spec. Some high apex length 45 mm. x height 13 mm. +0. stellifera 526 - 1 spec., low tide rock, Omapu. C. denticulata 528 - 3 spec, of this common southern on vertical exposed rock. *C. ornata 529 - as C. radians but on rough surfaces and extending rather further up shore. Littorinidae: •Melaraphe oliveri 551 - abundant all rock in high tide -^d ^ splash zones. Zelaxitas cystophora 558 - fairly common, seaweed was' Omapu. / Z. miera 559 - common, high tide pool, Opo. Bembiciidae: +Risellopsis varia 563 - high tide crevices •=> N. Opc 0 Rissoidae: +Estea semiplicata 598 - common in high tide pool,/^ E, nov. sp. cf. minor 600 - not common in high ti?z, N. Opo. (Type locality, Tauranga.^ ^Haurakia hamiltoni 616 - not uncommon, seaweed w° Omapu and Opo* . +Merelina lyalliana 625 common understones in , ditions just below mean low watf Merelina superba? 631 - 1 spec., ditto, Promerelina lacunosa 642 - 2 spec., high tide Notosetia infecta 667 - 1 spec- on sponge, lo North Opo. ( • +N. mi cans 671 - few spec, pool drift, North 0], o N. subcarinata 686 - uncommon, high tide pool, e5 if Scrobs semen 700 - uncommon, seaweed washings, h& § high tide pool, Opo. ^ *Dardanula olivacea 708 - common,, low tide, stones and weed, Opo and Omapu. 130.

Dardanula limbata 711 -2 spec, high tide pool, Opo. Rissoinidae: +Rissoina chathamensis 729 - not common, low tide pool and drift, Opo. — +R. rufolactea 736 - 2 spec., pools, North Opo. Cerithidae: +Zeacumantus subcarinatus 760 - common high tide pools, North Opo. +Joculator dirempus 787 - not common, on Microdictyoh in large, deep high tidal pool, North Opo. Vermetidae: Novastoa lamellosum 801 - low tide, Opo. Triphoridae: +Notosinister infel.ix 794 - on Microdictyon, deep, high tidaT pool, North Opo. Turritellidae: Zeaculpus fulminatus 813 - dead shells not uncommon, Omapu. Calyptraeidae: Maoricrypta (Zeacrypta) monoxyla 829 - common, low tide,Opo, Cymatidae: Mayena australasiana 869 - 2 specimens, low tide rocks, south Opo. Janthidae: Janthina (iodina) exigua 866 - dead shells, drift, Opo. Cominellidae: Cominella maculosa 1103-- 1 spec, low tide rocks, S.Opo. Muricidae: Zeatrophon ambiguus 1132 - 1 spec., dead drift, Omapu. Thaisidae: ^Neothais (Dicathais) scalaris 1163 - common low tide ledges and niches, rocks. ^Lepsiella scobina (albomarginata?) 1165 - common, inter- tidal rocks. Olividae: Baryspira australis 1238 - few dead shells, hermit crabs, Omapu. B. (Alocospira) novae zelandiae 1240 - ditto. B. (Pinguispira) depressa' 1 241 - ditto. Turridae: Antimelatoma buchanani maorum 1282 - 1 spec, of this deep water species washed up, Opo. Terebridae: Pervicacia tristis 1346 - uncommon, hermit crabs, Omapu. Aplysiidae: Tethys tryoni 1400 - 1 spec, washed up, Omapu. 131 *

Doridigitatidae; +Allolpdori ? 1423 - 1 spec*, low tide pool,N.Opo. Ellobiidae: *Leueono.psis obsoleta 1454 - high tide crevices, N.Opo, ^uīīeommon,

A M P H ī N E U R A

Lepidochitonidae.s. Paricoplax croclna 1771 - low tide pool, N. Opo. Gryptoconchidae: »Acanthochiton zelandicus• hooker! 1779 - ditto (7 valves)'. , Chitonidae: *Sypharochiton sin.clairl (Gray) 1810 - Midlittoral, common.

CEPHALOPODA

Spirulidae: - Spirula spirilla 1826 - drift, Opo. Ommastrephidae: NotoAQ^a£ug_ 1831 ~ 1 spec, washed up, N.W. Bay; 1 spec at Omapu, Octopodidae? ' *Qc^QP^.:5!..,"15?.1!1^ 1.845 ~ 1 spec , approx. 90 cms. under boulder, S-Opo reef. Argonautidae: *Argcnautanodosa ••- about 10 female specimens found, all but '"1852""'C'...ree 1 in, or less, about 8 cms.. One from ' N.W. Bay, 2 from Omapu, Most small ones from Omapu- 2 each from N.W. & Opo Bays. This mollusc is commonly found on the Island at this time of the year, evidently in shallow water while breeding. Perhaps seasonable weather accounted for their rarity on this occasion, However, many hundreds of the in­ conspicuous male were found washed up„ Opo Ba; 32.

MARINE MOLLUSCS

OP HEN ISLAND.

E.N. Milligan,

The area studied was limited to Old Woman's Cove which included dissected headland and sheltered rocks and boul• ders. Collecting was concentrated on the rock and boulder comm• unities for the purpose of making comparisons with equivalent comm• unities occurring at Little Bj.rrier and Mayor Is. Open rock usually shows a characteristic fauna for one province and this is probably due to the high degree of specialisation required in a more unfav• ourable environment. The greater variety of more favourable con• ditions among sheltered rocks allow ready colonisation by a variety of species and consequently comparisons within a single province can be more readily made in this habitat. At the head of Old Woman's Cove the rough stones and boulders were lying in sand from neap to higher tide levels. At neap tide the undersides of these stones were covered with large numbers of the Rissoid Merelina lyalliana and less comm• only with the bivalves Hochstetteria munita and Trichomuscuius bar- batus. Merelina was found occurring in the same manner on the sandy Omapu Bay stones of Mayor Is. but apparently without the other two species. At low tide spring the sand level dropped \ and the rocks were piled on one another, and covered with a e^" ^ pj\ uous mass of sponge and .ascidians. It was from here that ^$\o *A the records, came, ' o ®Y* %\ The following list (67 spp. and SL ^laV**?^ refers to species found in the Cove unless otherwise stated, '^©V* A

— ————— %\ $ P S L Y C OP 0 D A %K< Arcidae* Area nc vaeze ?•::•&-• -t 1 ae .-.. 28 - hot •uncommon, low tide spri. cj> ^ < Philobryidae: ^ o \ +Hochstette;rii>. munita. 43 - common between low. tide neap- ^% and spring. <£ CO Mytilidae: ^Trichomuscuius barbatus 60 - ditto. Pectinidae: -• • +Chlamy n (M ima chl amy s). z el andiae 73 - 1 spec,a low tide spring. Carditidae: +Cardita_ aoteana 129 - 2 juvenile spp*, low tide spring. 133.

Ostreidae: Grassostrea ( = Saxostrea) glomerata 100 - mid tide, Old- Woman Rock. Leptonidae: ~ ~ Lasaea maoria 166 - common, high tide crevices. Hiatellidae: +H-iatella australis 2~J3 - common, low tide spring.

G A S T S R 0 P 0 D..A

Haliotidae: . . . *Hallotus (Paua) iris 313 rare, on sides of stones, probably due to uneven rock surfaces.. -

Fissurellidae: +Tugali elegans 321 - 1 juvenile spec., low tide spring. Trochidae: - *Thoristella oppressa 346 - common under stones below low tide neap. +Melagraphia aethiops 351 - common, mid tide. +Zediloma morio 358 - ditto. *Anisodiloma lugubris 360 - common under stones, low tide neap. ^Microlenchus dilatatus 377 - common, low tide seaweed. Stomatellidae: *Herpetopoma bella 381 - common, low tide. Liotiidae: (pool. Lodderia iota 423 - 1 spec, Corallina washings, low tide Turbinidae: ^Lunella smaragda 488 - common, low tide. +Cookia sulcata 491 - ditto. Neritidae: +Nerita (Melanerita) melanotragus 493 - common, mid tide. Patelloididae: •fPatelloida corticata corallina 501 common, mid tide. + Radiacmea inconspicua 504 - common, low tide spring. *.Notoacmea pileopsis 509 - common, Old Woman Rock. *N.. pileopsis cellanoides 510 -recorded from island. *Atalacmea fragilis 521 - uncommon, low tide neap.< Patellidae: *Cellana radians 523 - common, mid tide. +C, stellifera 52? - 1 juv. spec, low tide, spring. *C. ornata 529 - common, mid tide. Littorinidae: *Melaraphe oliveri 551 - abundant, high tide. Bembiciidae: +Risellopsis varia 563 - common, high tide. 134.

Rissoidae: +Estea impressa 594 --not tin common, low tide. ^Haurakia hamiltoni 616 - common, low tide, Corallina pool. +Merelina lyalliana 625 - extremely abundant, smothering sandy stones just above low tide spring. 5*Dardanula olivacea 708 - common, low tide pools & seaweed. D. limbata 711 - 1 spec., low tide under stone. Larochella alta 726 - 1 spec., low tide, Corallina pool. Rissoinidae: . +Rissoina chathamensis 729 - common under stones, low tide, spring. +R. rufolactea 736 - 1 spec., low tide, Corallina pool. Cerithiidae: Zacays sarissa 782 - 1 spec, under stone, low tide spring. +Joculator dirempus 787 - 1 spec., ditto.• Triphoridae: +Notosinister infelix 794 - not uncommon, ditto. N. ampullus 795 uncommon, ditto. Vermedbidae: +Stephopoma roseum 802 - uncommon, low tide. Cymatidae: +Mayena australasia 869'- uncommon, low tide. i-irchitectonicidae: Philjppia lutea 905 -1 spec, of this very rare mollusc was found on sponge under a stone at extreme low tide by R. Bieleski. ••; :. Fasciolariidae: * Tar on dub i us 1025 - not common, low tide. Mitridae: +Austromitra rubiginosa 1034 - uncommon, low tide, stones. Buccinulidae: +Buccinulum (Euthrena) heteromorphum 1071 - quite uncommon, ditto. Cominellidae: +Cominella virgata 1104 - not common, ditto. Thaisidae: ^Neothais (Dicathais) scalaris 1163 - low tide ledges. »Lepsia haustrum 1164 - ditto. ^Lepsiella scobina albomarginata 1166 - mid tide. Pleurobranchidae: +Bouvieria ornata 1404 - not uncommon, low tide, spring. Doridigitatidae: +Alloiodoris lanuginata? 1423 - 1 spec, low tide spring. Glossodoris aureomarginata 1426 - uncommon, ditto. Ceratosoma amoena 1428 - ditto, Doriobsidae: Dendrodoris citrina 1434 - not uncommon, ditto. 133.

Aeolidiidae: One specimen of an Aeolid nudibranch as follows: 1 pair of buccal tentacles; 1 pair of pustulate rhinophores approx• imate at their bases. Two ventrolateral lobes below the mouth running posteriorly and joined for 2/3 their length by flaps to the body. Hepatic cerata numerous, extending anterior to the rhinophores. Anterior cerata clustered to form a group on either side from which a continuous row- passes back on either side of the body. Colour: pink, buccal tentacles orange, rhinophores orange with red pustules and white tipped; hepatic cerata purple- reddish brown; white circle with white dot in centre be• tween tentacles and rhinophores; white dots down centre of back. This attractive nudibranch was found under sponge-covered stone in the infralittoral fringe. Possibly a new species.

Ellobiidae: +Leuconopsis obsoleta 1454 - high tide crevices Siphonariidae: +Siphonaria zelandica 1458 - mid tide pools. Onchidiidae: Qnchidella nigricans 1752 - low tide.

AMPH INEURA

Ischnochitonidae: +Ischno.chiton maorianus 1755 - common under low tide stones. Cryptoconchidae: (stones. Cryptoconchus porosus 1777 - not uncommon under low tide ^Acanthochiton zelandicus hookeri 1779 - ditto. +Notoplax violacea 1783 - 1 juv. spec., ditto. Chitonidae: +Amaurochiton glaucus 1808 - common under low tide stones. * P.•.'pharo-chiton pello serpent is 1809 - common, mid-tide. +S. Sinclairi 1810 - common, low-tide. 136.

MARINE MOLLUSCS

LITTLE BARRIER

E.N. Milligan.

Five habitats were found on the island: 1) Pebble beach. Here the rocks are smooth and exposed, and form an unstable substrate. .tfhis smooth rounded surface and constant crushing movement greatly reduces chances of colonisation; also it precludes formation of such suitable habitats as rock pools and crevices. Consequently the molluscan fauna here is limited, although at lowest tide where -the stones are heavier and there is ,less movement, less highly adapted species sometimes appear. 2) Larger rocks, predominantly immobile. This habitat is not so harsh in that it is more stable) but still crevice and pool species are absent. 3) Open rock, the most exposed being Ngatamahine Rocks. 4) Sheltered reef conditions giving a wide variety of favourable conditions for many molluscs. 3) Only a. few patches of sand occurred as surface substrate. Two species were found under stones in contact with it.

A total of 75 species and subspecies were recorded.

P E L E C Y P Q D A

Glycymeridae: +Glycymeris laticostata 30-1 dead spec., sublittoral, off south coast. Mytilidae: +Modiolus neozelanicus 64 - rare, Te Hue P(b, mid-tidal. Modiolus, areolatus 65 - 1 spec, dead, attached Ecklonia base, *Trichomuscuius barbatus 68-2 spec., Ngatamahine Rocks, mid tide, pool crevice. Pectinidae: +Chlamys (Mimachlamys) zelandiae 73-1 spec., low water spring under stable stones, South Titoki. Ostreidae: *Crassostrea (= Saxostrea) glomerata 100 - confined to mid- tide platforms sheltered from full wave ex• posure, Hingaia, Ngatamahine Rocks. Leptonidae: +Lasaea hinemoa 165 - common, high tide, crevices, Te Hue- Ngatamahine Rocks. 137.

Hiatellidae: +Hiatella australis 273 - common, high water, Te Hue and under Ecklonia base. ....

G A S'-T-E- R 0 P 0 D A Scissurellidae: •i-Scissurona rosea 305 - 1 spec. , low tide, spring. Te Hue. Haliotidae: ;:*Haliotis (Paua) iris 313 - low spring, not uncommon under more stable boulders and at Te. Hue reef. H. (Notohaliotis) australis 314 - 1 spec, low spring,Te Hue. Fissurellidae: +Tugali elegans 321 - low tide spring, few juveniles under more stable stones at Hingaia reef. +T. suteri bascauda 325 - low tide, not uncommon, Hingaia and Te Hue. Trochidae: Trochus (Thorista) viridus 339 - uncommon, low water neap, Te Hue and Hingaia Reef. •^Thoristella oppressa 346 - common, ditto. -HMelagraphia aethiops 351 - mid- tide, not common, pebble beach. Becomes more common from exposed to more sheltered rock. Zediloma digna 352 - abundant mid-tide, on decaying Ecklonia, pebble & boulder beach. Z. (Fractarmilla) atrovirens 357 - mid tide in small area at N. Titoki, found smothering decaying Ecklonia. +Z. (Fractarmilla) morio 358 - common, high tide, pebble boulders, open rock. *Anisodiloma lugubris 360 - common, high tide, under stones. Micrelenchus rufozonus 375 - 1 dead spec., sublittoral, off south coast. Micrelenchus dilatatus 377 - common, on Ecklonia and Carpo• phyllum. Hingaia and Te Hue, +Fossarina rimata 380 - common, high tide crevices, Te Hue. Stomatellidae: ^Herpetapoma bella 381 - common, high tide under stones, Te Hue. Calliostomatidae: Venustus (Mucrinops) punctulata 401 - 1 live specimen in mid-tide pool, Ngatamahine rocks. This was possibly washed from its sublittoral habi• tat by a storm. Turbinidae: ^Lunella smaragda 488 - low tide under stable rocks, E.Cape. Rocks and Carpophyllum. Te Hue and Hingaia. Large specimen, 65 x 60 mm. 138.

+Cookia sulcata 491 - low tide as last, and also mid-tide, pool, Ngatamahine. Neritidae: +Nerita (Melanerita) melanotragus 493 - the most abundant mollusc of the pebble and boulder beaches, dotting the mid-tidal region with its con• spicuous black shell, Patelloididae: ' +Patelloida corticata corallina 501 - common, mid-tide, open rock. +Radiacmea inconspicua 504 - common, low tide on Paua and coralline rocks, Te Hue and Hingaia. *Notoacmea pileopsis 509 - common, high tide on exposed rock. *N. pileopsis cellanoides 510 - uncommon, as last, confined -to rough surfaces near Crayfish Rock and Te Hue (type locality Little Barrier). +N. (Parvacmea) daedala 513 - common, low tide under smooth stones, pebble beach and reefs. *Atalacmea fragilis 521 - ditto, uncommon in reef conditions. Patellidae: ^-Cellana radians 523 - abundant,, mid-low tide pebble beach, reef and open rock. +.C. s^ellifera 526 - 2 specimens only, under stones, high tide, spring. Te Hue reef, ^C. ornata 529 - common, confined mainly to uneven surfaces, boulders and open rock. Littorinidae: »MeXarHaphe oliveri 551 w abundant, high tide, spring, Bembiciidae: *Risellopsis varia 563 - common, high tide crevices, Te Hue. Rissoidae: Bstea zosterophlla 592 - common, under low tide stones, Te Hue. +B. impressa 594 - not uncommon, ditto. E. subfusca 596 - not uncommon, ditto. ^Haurakia hamiltoni 616 - 2 spec, ditto. Merelina taupoensis 629 - 1 spec, mid tide pools, sponge, Ngatamahine. ^Dardanula olivacea 708 - very common, low tide stones,reefs, Assimineidae: Suterilla neozelanica 759 - not uncommon In storm bank deb• ris where Pohutukawa shade prevented some drying out. Triphoridae: Notosinister fascelinus 793 - 1 dead spec., Ngatamahine. +N. infelix 794 - under stones, high tide spring, Te Hue. Vermetidae: +Stephanopoma roseum 803 - 1 dead spec, in drift, south coast. Cymatidae: Charonia capax 865 - occasionally in. drift,.one spec, washed •up alive, south landing, August, •fMayena australasia 869 - occasionally in drift. Fasciolaridae: • -. , •,. ^ Tar on dubius 1025 - not common, low tide s't one's,'Te Hue'. Mitridae: 7 •> : ' +Austromitra rubiginosa 1034 - uncommon, ditto. Buccinulidae: Buccinulum lineum 1045 - 1 live spec, mid-tide pool, Ngatamahine. See Venustus. Cominellidae: Comihella quoyana 1113 - common, sublittoral on fishing hooks, few hundred yards off South coast. Thaisidae: "•'Neothais (Dicathais) scalar is 1163 - common under ledges, open rock (juveniles under low tide stones) *Lepsia haustrum 116-6 - less oommon, under ledges. *Lepsiella scobina albomarginata 1165 - abundant, open rock. Pyrenidae: Zemitrella chaova 1180 - 1 spec, low tide stones, Te Hue. Paxula paxillus 1197 - low tide stones, Te Hue, and stones in sand near Shag colony. Pleurobranchidae: +Bouvieria ornata 1404 - 1 spec., low tide, spring, under stable rock, Titoki south landing. Doridigitatidae: Ctenodoris flabe.llifera 1420 - ditto. Halgerdidae: Aphelodoris affinis 1431 - low tide, 1 spec, on Carpo- , phyllum, Te Hue. Ellobiidae: Marinula filholi 1451 - common high tide, a few mid-tide, pebble beach. ^Leuconopsis obsoleta 1454 - common, high tide crevices, Te Hue. Siphonariidae: *Siphonaria, zelandica 1458 - mid tide to high tide, neap, rock and boulders. Common. Onchidiidae: Onchidella patelloides 1754 - common, low tide neap, Te Hue.

AMPHINEURA

Ischnochitonidae: +Ischnochiton maorianus 1755 - common under low tide stones. 140.

Lepidochitonidae: -t-Eudoxochiton nobilis 1774 - fairly common, exposed rock. Haingaia. Cryptoconchidae: *Acanthochiton zelandicus hookeri 1778 - low tide under stones, East Cape. Plaxiphoridae: Guildingia obtecta 1798 - 1 juv. spec, in mid-tide pool, Hingaia. Chitonidae: ^Amaurochiton glaucus 1808 - under stones, low tide, E.Cape. Large spec., 47 mm. x 30 mm. ^Sypharochiton pelliserpentis 1809 - common, exposed rock. •fOnithochiton neglectus 1812 - few specimens, low tide stones, Te Hue.

CEPHALOPODA

Ar gonautIda e: •fArgonauta nodosa 1852 - rarely specimens are found washed up here.

GENERAL DISCUSSION

With reference to the three lists, a high co-incidence of species is at once evident. In fact, such species dominate the lists. This is not surprising as all 3 islands lie in the same (Aupourian) Province, and all experience . roughly the same wave exposure. Many of these records are widespread,, common open rock forms; but a large number, including some rather un• common species, are from low tide under stones where wave exposure is a relatively unimportant factor. The probable reason lies in the volcanic rocks of the islands and the quickly shelving adjacent sea floors supplying a similar substrate in each locality. Most of the species found on one island only ' were from habitats found only on that island; e.g. pebble beach on Little Barrier and sandy beach on Mayor Is.: others are very small species which may have been over• looked elsewhere. Many of the genera, especially at. Hen. Is., show tropical and subtropical affinities, particularly Australian relationships; as is typical of the Aupourian Province; e.g. the Nudibranchs Glossodoris, Ceratosoma, Dendrodoris and Argonauta and Philippea. However, it is interesting to notice also the infil• tration of species from the cold temperate Fosterian province, aided by currents running up the East Coast. At Mayor Is. we find Cellana denticulata, found commonly in Otago but limited mainly to Kaikoura, Cape Kidnappers, East Cape, Poor Knights', North Cape and Three 141 .

Kings in the north. Notoacmea pileopsis cellanoidesc very much like N. pileopsis pileopsis at Banks Peninsula, has achieved subspecific rank at the type locality - Little Barrier (Oliver)..... Zediloma digna. a form feeding on Durvillea at Wellington and further south, has been carried north to the West Coast (Powell) and is found at Little Barrier feeding on decaying Ecklonia.

References:

Oliver, W.R.B. 1926, "Australasian Patelloididae." Trans. N.Z. Inst., Vol. 56. Powell, A.W.B. 1924. "Notes on New Zealand ." N.Z.

Journ. Sci. & Tech.9 Vol. 4, no,. 4. ~ 1946. "Shellfish of New Zealand." Whitcombe & Tombs Ltd. — — . 1953» "Additions to the Recent Molluscan Fauna of New Zealand." Bull. Conch. Sect. Auck. Mus. & Inst, , No. 9.

Thomsony J.M. 1954» "The Genero of Oysters." Aust. Journ. Marine & F.W. Research. Vol. 5, no. 1.