. Bulletin of the Museum of Comparative Zoology at Harvard College. Zoology. 284 Bulletin Mmcuni of Comparative Zoology, Vol. 145, No. 6 siphonol retractor muscle. palp proboscis mantle edge Figure 22. Silicula mcalesteri Allen and Sanders. Trans- verse section through posterior adductor muscle, gills and palp proboscides. margin is not intact. Though the type is reminiscent of S. mcalesteri the teeth ap- pear thicker and, because S. patagonica is from the eastern Pacific, we decided to consider these as separate entities. The present species is named in honour of Dr. A. Lee McAlester, Departm
. Bulletin of the Museum of Comparative Zoology at Harvard College. Zoology. 284 Bulletin Mmcuni of Comparative Zoology, Vol. 145, No. 6 siphonol retractor muscle. palp proboscis mantle edge Figure 22. Silicula mcalesteri Allen and Sanders. Trans- verse section through posterior adductor muscle, gills and palp proboscides. margin is not intact. Though the type is reminiscent of S. mcalesteri the teeth ap- pear thicker and, because S. patagonica is from the eastern Pacific, we decided to consider these as separate entities. The present species is named in honour of Dr. A. Lee McAlester, Department of Geology and Geophysics, Yale University, for his keen and perceptive contributions to the evolutionary history of the protobranch bivalves. The shell of this .species is sufficiently transparent for us to appraise the state of maturity and sex of the animals in our sam- ple. Only the two specimens smaller than 4 mm were not mature; one was immature and the other showed incipient gonad de- velopment. The sexes are separate and present in our sample in essentially equal numbers, 23 females and 24 males. In the region of broad overlap, mm, males and females were equally abundant (Fig. 24). The three mature specimens smaller than mm were females and each of the five individuals larger than mm were males, suggesting a possible size dif- ferential in the sexes. The mature egg is small (90 /Lt) for a protobranch and accord- ing to the criteria of Ockelmann (1965) this size would make it barely lecithotrophic. We estimate that about 1,000 ripe eggs were present in the one specimen examined. Siliculo rouchi Lamy, 1910 Figures 25-27 Silicula rouchi Lamy, 1910: 394 (Type locality: Alexander Island, Antarctica; type specimen: Mus. natl. Hist, nat., Paris); 1911: 30. Hedley, 1916: 18. Soot-Ryen, 1951: 6. Carcelles, 1953: 208. Powell, 1958: 171; 1960: 171. Dell, 1964: 147. Nicol, 1966: 15. Dell, 1969, folio 11. Although this species is not represented in our colle
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