. Bulletin of the Museum of Comparative Zoology at Harvard College. Zoology. Deep Sea PRt)TC)BRANCHS • Allen and Sanders 17 lies posterior to the pedal ganglion but barely penetrates the foot below the level of the pedal ganglion (Fig. 13). Because there are so few large speci- mens, none were opened to obsei^ve the condition of the gonads. However, the smallest specimen to show signs of go- nadal development was a male, mm in total length. In this specimen, the tes- tis was in a very early stage of develop- ment and tenuously covered both the posterior part of the coiled hind gut on the r
. Bulletin of the Museum of Comparative Zoology at Harvard College. Zoology. Deep Sea PRt)TC)BRANCHS • Allen and Sanders 17 lies posterior to the pedal ganglion but barely penetrates the foot below the level of the pedal ganglion (Fig. 13). Because there are so few large speci- mens, none were opened to obsei^ve the condition of the gonads. However, the smallest specimen to show signs of go- nadal development was a male, mm in total length. In this specimen, the tes- tis was in a very early stage of develop- ment and tenuously covered both the posterior part of the coiled hind gut on the right and the digestive diverticula on the left. There was little development of gonadal tissue in other specimens. Growth stages from the Angola Basin (Station 195) and the Brazil Basin (Station 156) were examined. The larger speci- mens from the eastern Atlantic tend to have a sharper rostrum than similar sized specimens from the west (Fig. 14). Slight interpopulation differences in lateral out- line did not exceed variation exhibited in a single sample. In the course of growth, the rostrum becomes more pronounced (note a gradual change in the total length/ umbo-rostral length ratio, Fig. 15). The postero-ventral margin is more angular in young stages than in older shells, but there is little or no change in the height/ length ratio. We have no doubt that the populations of the various basins belong to one and the same species. The larval shell measures 420 fjcm. Spinula scheltemai new species Figures 16-21 + 28 Holotype: MCZ 279905. (Type localit>: ATLANTIS II, Cruise 60, Station 242, Argentine Basin, Lat. 38°'S, Long. 'W, in 4382^405 m.) Records: Argentine and Guiana Basins. Depth range = 3305^405 m. Specific Description. Shell inequilat- eral, laterally compressed, obliquely ob- long/oval in outline, with strong, even concentric lines; rostrum well developed and sharply pointed; umbos anterior and low in profile, very small in larger spec- imens, more poster
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