BULLETIN OF THE GEOLOGICAL SOCIETY OF AMERICA

VOL. 67. PP. 679-682.1 PL. MAY 1956

TYPES OF BATHYURISCUS HOWELLI VAR. LODENSIS CLARK

BY ALEXANDER STOYANOW

The status of Bathyuriscus howelli var. "This is probably new, but the cepha- lons of all the specimens were crushed so that the lodensis Clark from the Middle of original characters could not be accurately deter- southern California, as presented in the litera- mined. It is referred to B. howelli as it has eight thoracic segments (italics mine) and seems to cor- ture, has been discussed recently by Stoyanow respond to this species excepting in the fifth seg- and Susuki (1955, p. 467) as follows: ment, which is broader than any of the others and terminates in a long spine that curves well back "A of the Anoria-Glossopleura group toward the pygidium. It is therefore called B. but with eight thoracic segments, collected from howelli var. lodensis." the Middle Cambrian strata in Bristol Mountains, southern California, was described as Bathyuriscus howelli var. lodensis by Clark (1921, p. 6) but was In this statement is a direct reference to the not figured. Later Resser (1928, p. 10, PL 3, fig. 9) presence of eight thoracic segments, in com- illustrated Clark's type advancing it to the status plete agreement with Clark's upper example as of species, Dolichometopus? lodensis (Clark), and also mentioned eight thoracic segments. However, in Resser's Figure 9 (Resser, 1928, PL 3). For in a more recent paper Resser (1935, p. 29, 34) some reason Resser omitted mention of the placed this species, as Glossopleura lodensis (Clark), with other species possessing only seven thoracic eighth segment, albeit it is plainly visible in segments, as also did Mason (1935, p. 109, PI. 15, his illustration (PL 1, fig. 1). As to the macro- fig. 11) while describing, as Anoria lodensis, a pleural segments, the figure shows both the plesiotype of Clark's species collected in Marble Mountains. Like Anoria, Clark's species has a fifth and the sixth segments enlarged, and the macropleural fifth thoracic segment. The illustra- sixth possibly even more so. tions of Resser and Mason do not allow the figur- Regarding the smaller trilobite, with ques- ing of the number of thoracic segments (eight as by Clark, or seven as by Resser and Mason) in tionable number of thoracic segments, the either of the two types with any degree of assur- lower illustration of Resser's Figure 9, which he ance. Clark's holotype was not available at the finally designated as the holotype of his Glosso- time of this writing, but Mason's plesiotype, pre- served in the Los Angeles Museum, has been ex- pleura lodensis (Clark), it should be noted that amined by the writers through the kindness of this type cannot be placed under Glossopleura Dr. G. P. Kanakoff. It has seven thoracic segments with the fifth segment macropleural as in Anoria," Poulsen (1927, p. 268) since according to Poulsen's generic definition the absence of the Clark's rock specimen, USNM 78400, il- macropleural development in the fifth thoracic lustrated by Resser (1928, PI. 3, fig. 9), shows segment is one of the cardinal characteristics of two without individual numbers—a Glossopleura by which it is distinguished from smaller trilobite in the lower part of his illustra- Anoria Walcott. This trilobite is congeneric, tion, which he selected (Resser, 1928, p. 14; and to all evidence conspecific, with the topo- 1935, p. 34) as holotype of Clark's species, and type-plesiotype, which has the fifth thoracic which alone, in accordance with Resser's segment macropleural, described and illustrated designation, was regarded as the holotype by by Mason (1935, p. 109, PL 15, fig. 11) as Stoyanow and Susuki (1955); and another, Anoria lodensis (Clark). The topotype has only much larger trilobite in the upper part of the seven thoracic segments as mentioned by same illustration. This larger trilobite was at Mason and as checked by Stoyanow and first identified by Resser (1928, p. 10, 14) as Susuki. Originally Mason (1935, p. 109, 118) Dolichometopus productus (Hall and Whitfield) placed it in Anoria Walcott, but following but later designated as Glossopleura mohavensis Resser's publication of 1935 he moved it to Resser (1935, p. 34). These two trilobites are Glossopleura, notwithstanding the macro- two different species and possibly may belong pleural fifth segment in the thorax (Mason, in two different genera. 1935, p. 117). Both Clark's and Mason's Clark's brief reference to his Bathyuriscus examples have a long and narrow macropleural howelli var. lodensis reads: thoracic segment, clearly marked from the 679

Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/67/5/679/3431808/i0016-7606-67-5-679.pdf by guest on 24 September 2021 680 ALEXANDER STOYANOW—BATHYURISCUS HOWELLI VAR.

rest, and similar facial sutures with strongly (PI. 1, fig. 3). Such a development is also ob- curved, nearly semicircular, palpebral lobes, servable in the right side of Mason's example, the latter feature regarded by Mason as a and I have seen it in several cranidia of the distinction from Anoria tontoensis (Walcott, Anoria-Glossopleura material from the Grand 1916, p. 373, PI. 51, figs. Ic, Id; 1924, p. 54, Canyon. If this interpretation is correct, Resser PL 9, fig. 2; 1925, p. 68, PL 18, fig. 20). was right in assuming seven thoracic segments In Mason's topotype the entire axial part of in the example which he selected as holotype of the thorax is destroyed, but Clark, Resser, and Clark's species. This, however, would disagree Mason did not mention an axial tuberculation with the fundamental part of Clark's diagnosis. in Clark's type selected by Resser as holotype It is interesting that Mason (1935, p. 110) re- of Clark's species, and indeed Resser's illustra- futed the presence of the eighth segment in the tion of this smaller specimen shows an un- smaller trilobite in believing that the thickened tuberculated thorax (PL 1, fig. 1); the absence anterior edge of the pygidium of the holotype of this characteristic would further remove was mistaken for an eighth segment. This this species from Anoria Walcott and probably species differs from Glossopleura by the macro- has served as a determining factor in Resser's pleural development and from Anoria by the placing it, as well as Clark's larger specimen, in lack of axial tuberculation. Whether it may be Glossopleura. placed in Sonoraspis will depend on the veri- Dr. G. Arthur Cooper very kindly examined fication of the number of thoracic segments in Clark's specimen, USNM 78400. Although the better-preserved topotypes. cephalon of the smaller specimen is somewhat The larger specimen illustrated by Resser is offset and crushed, a "lip" of what might have described here. been the eighth (that is the first thoracic) seg- ment is in evidence. In the larger trilobite, with Sonoraspis mohavensis (Resser) eight thoracic segments, it is difficult to decide (PL 1, fig. 1) which segment is the larger, the fifth, or the sixth. Actually the fifth seems a little larger BathyurisGus howetti var. lodensis CLARK (part), 1921, Univ. Calif., Dept. Geol. Sci. Bull., v. (measured in the direction of long axis), but 13, p. 6 the segmental spine is decidedly smaller than Dolichometopus productus (Hall and Whitfield) that of the sixth segment. Doctor Cooper was RESSER, 1928, Smithsonian Misc. Coll., v. 81, no. 2, p. 10 and 14, PL 3, fig. 9 (upper part unable to find an ornamentation on any part of only) either trilobite. He mentioned, however, as the Glossopleura mohavensis RESSER, 1935, Smithsonian illustration shows, that the axial crest in the Misc. Coll., v. 93, no. 5, p. 34. (Specimen illus- trated in the upper part of Resser's Figure 9 larger trilobite has been stripped off (Cooper, of Plate 3, publication of 1928, assigned here Personal communication). as holotype of this species) Subsequently Doctor Cooper sent me a rub- ber cast of Clark's specimen (PI. 1,fig. 2). I think This species, in agreement with other described the "lip" in the smaller trilobite is a thickening species of Sonoraspis Stoyanow, differs from Anoria (Walcott) and Glossopleura Poulsen by the presence and a furrow which developed in the posterior of eight segments in the thorax. It is distinguished margin of the posterolateral limbs. Similar from other species of the first by the macro- swelling and groove have been illustrated by pleural development in the thorax—the fifth seg- Walcott (1918, PL 14, fig. 1, right side; PL 16, ment as in Clark's text, the sixth segment as in fig. 3, right side) for Olenoides ("Neolenus") Resser's illustration. Of importance is the fact that

PLATE 1.—INTERPRETATION OF THE NUMBER OF THORACIC SEGMENTS IN CLARK'S TYPES FIGURE 1.—Reproduction of Resser's photographic illustration taken from Clark's original, USNM 78400 Note eight thoracic segments in the upper specimen; GS—genal spine; MP—the fifth and the sixth macropleural segments, FIGURE 2.—Rubber cast of Glossopleura lodensis (Clark) by Resser's designation, USNM 78400, the lower specimen of Figure 1 A—groove between two salients below the posterolateral furrow. FIGURE 3.—Walcott's illustration of Olenoides serratus (Rominger), USNM 58591 PLF—posterolateral furrow; A—groove between two salients below.

Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/67/5/679/3431808/i0016-7606-67-5-679.pdf by guest on 24 September 2021 BULL. QEOL. SOC. AM., VOL. 67 STOYANOW, PL. 1

------

------

------

INTERPRETATION OF THE NUMBER OF THORACIC SEGMENTS IN CLARK'S TYPES

Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/67/5/679/3431808/i0016-7606-67-5-679.pdf by guest on 24 September 2021 SHORT NOTES 681

according to the mentioned illustration the pleurae and Canadian faunas of northwest Greenland: Meddelelser om Grjfoland, v. 70, p. 233-343, of the longer-spined macropleural segment overlap Pis. 14-21 the two last posterior thoracic segments exactly as in Resser, Charles E., 1928, Cambrian fossils from the Anoria. The left part of the cephalon is not pre- Mohave Desert: Smithson. Misc. Coll., v. 81, served in Clark's type, but the Anoria-]ike course no. 2, p. 1-14, Pis. 1-3 1935, Nomenclature of some Cambrian trilo- of the facial suture visible in its right part is as in bites: Smithson. Misc. Coll., v. 93, no. 5, p. 5. torresi Stoyanow (1952, p. 53, PI. 14, fig. 3) and in 1-46 5. californica Stoyanow and Susuki (1955, p. 468, Stoyanow, Alexander, 1952, The original collection PI. 1, figs. 1, 2). The axial part of the thorax does of Cambrian trilobites from Sonora in Cam- brian stratigraphy and paleontology near not seem to be satisfactorily preserved in the type, Caborca, northwestern Sonora, Mexico: Smith- but, since Clark, Resser, and Mason do not mention son. Misc. Coll., v. 119, no. 1, p. 49-59, PI. 14 the presence of axial tubercles, it may be presumed Stoyanow, Alexander, and Susuki, Takeo, 1955, that, as in S. torresi, the thoracic axis of this species Discovery of Sonoraspis in southern Califor- nia: Geol. Soc. America Bull., v. 66, p. 467- is untuberculated, unlike the thoracic segments of 470, Pis. 1-2 5. gomezi Stoyanow (1952, p. 54, PI. 14, figs. 5, 6) Walcott, Charles D., 1916, Cambrian geology and and S. californica which bear the axial tubercles. paleontology. Cambrian trilobites: Smithson. Type: Holotype, U S N M 78400, larger specimen Misc. Coll., v. 64, no. 5, p. 303-456, Pis. 45-67 only 1918, Cambrian geology and paleontology. Appendages of trilobites: Smithson. Misc. Occurrence: Middle Cambrian, Bristol Moun- Coll., v. 67, no. 4, p. 115-216, Pis. 14-42 tains, southern California 1924, Cambrian geology and paleontology. Cambrian and lower Ozarkian trilobites: Smithson. Misc. Coll., v. 75, no. 2, p. 53-60, REFERENCES CITED Pis. 9-14 1925, Cambrian geology and paleontology. Clark, C. W., 1921, Lower and Middle Cambrian Cambrian and Ozarkian trilobites: Smithson. formations of the Mohave Desert: Univ. Calif. Misc. Coll., v. 75, no. 3, p. 61-146, Pis. 15-24 Dept. Geol. Sci. Bull., v. 13, p. 1-7 Mason, John F., 1935, Fauna of the Cambrian UNIVERSITY OF ARIZONA, TUSCON, ARIZ., AND Cadiz formation, Marble Mountains, Califor- UNIVERSITY OF CALIFORNIA, Los ANGELES, nia: Southern Calif. Acad. Sci. Bull., v. 34, CALIF. pt. 2, p. 97-119, PI. 15 MANUSCRIPT RECEIVED BY THE SECRETARY OF THE Poulsen, Chr., 1927, The Cambrian, Ozarkian, SOCIETY, NOVEMBER 30, 1955

Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/67/5/679/3431808/i0016-7606-67-5-679.pdf by guest on 24 September 2021