. Bulletin of the Museum of Comparative Zoology at Harvard College. Zoology. Deep Sea Protobranchs • Allen and Sanders 19. Figure 16. Spinula scheltemai. A. External view of right valve of holotype (MCZ 279905) from Station 242. B. Internal view of a left valve from the same station and lateral view of the ligament removed from the hinge plate, a, b, and c, transverse sections through the internal ligament (resilium) and external ligament at the points indicated by the broken lines. Abbreviations: P, periostracal layer; IL, inner layer; OL, outer layer. ately anterior to the umbo. The hinge pl
. Bulletin of the Museum of Comparative Zoology at Harvard College. Zoology. Deep Sea Protobranchs • Allen and Sanders 19. Figure 16. Spinula scheltemai. A. External view of right valve of holotype (MCZ 279905) from Station 242. B. Internal view of a left valve from the same station and lateral view of the ligament removed from the hinge plate, a, b, and c, transverse sections through the internal ligament (resilium) and external ligament at the points indicated by the broken lines. Abbreviations: P, periostracal layer; IL, inner layer; OL, outer layer. ately anterior to the umbo. The hinge plate is more slender in S. oceanica with the teeth even closer to the dorsal mar- gin. The external ligament is at least twice as long in S. scheltemai as in S. oceanica and larger than in any other species recorded here. We name this species after our friend and colleague Dr. Rudolf Scheltema of the Woods Hole Oceanographic Institu- tion. Morphology. Although the form of the body and mantle is similar to that of other species, the body of S. scheltemai occu- pies more shell space than any other species (Fig. 17). The adductor muscles are much closer to the shell margin, par- ticularly the posterior, possibly because the rostrum of S. scheltemai is not greatly extended. The adductor muscles are ver>' large, while the siphonal embayment is short. The anterior sense organ is far an- terior in position, but because the adduc- tor muscle lies close to the shell margin, the sense organ is situated immediately below the muscle. The palps are relatively much larger than in the other species described here. Depending on the size of the animal, 26- 50 ridges are present, the palps extend- ing across the entire width of the body. The palp proboscides are ver\- short in the preserved specimens and fill the space between the ventral edge of the gill and the posterior edge of the palp. The gills are moderately well developed with about 25 gill plates to each demi- branch. The ganglia ar
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