186 PROCEEDINGS OF THE ACADEMY OF 



ginals (fig. b) are but a modification of these laterals, by the 

 greater development of the reflection, and shortening of the inner 

 cusp. The outer marginals (fig. c) become wide, low, irregular in 

 shape; the upper edge broadly reflected, the reflection reaching 

 the lower edge of the base of attachment, and bearing along its 

 whole length numerous (6 or 8 in some teeth) short subequal 

 denticles, some bluntly rounded, others longer and sharp, giving 

 a pectinate appearance. 



My study of this membrane confirms my belief of the identity 

 of the species with the European form. I have carefully compared 

 the dentition of our form with that described and figured by 

 Lehmann (Lebenden Schnecken, 132, pi. XIII., fig. 44), and find 

 them to agree. I must, therefore, disagree with the decision of 

 Morse (Journ. Portl. Soc). I have also examined the genitalia 

 of our species, and found it to agree with Lehmann's figure (1. c), 

 especially in the existence of the very peculiar flagellum to the 

 penis sac. This, however, cannot be considered as a most reliable 

 specific character peculiar to this species, as it exists also in Gseci 

 lianella acicula. 



I am very confident of the presence of well-developed side cusps 

 to the central teeth, which Morse (1. c.) does not figure, though 

 they are figured by Thomson, Ann. Mag. N. H., VII., pi. IT., fig. 

 8. They appear to me also to bear the short cutting points which 

 I have figured. 



Genus C.ECILIANELLA, Bourg. 



I have not been able to examine the jaw or dentition of G. aci- 

 cula (Cionella acicula of L. and Frw. Shells, I. 221), the only 

 species found in our limits. They are both well known, however, 

 from the descriptions and figures of Moquin-Tandon, Thomson, 

 Sordelli, 1 and Lehmann. The jaw is low, wide, arcuate, with deli- 

 cate vertical striae. The lingual membrane (Lehmann, Lebenden 

 Schnecken, p. 128, pi. XIII., fig. 43) has 120 rows of 11111 

 teeth each. The centrals are small, tricuspid (Sordelli), the 

 laterals, six in number, are larger, and have a more highly devel- 

 oped reflection, and are also distinctly tricuspid. Marginals sub- 

 quadrate, with a broad reflection, bearing delicate denticles. 



1 Sordelli (Atti della Soc. Italiana di Sc. Nat. XIII., fasc. 1, p. 50, pi. i. 

 f. 25) describes the ribs to be not straight, but curving, with a median point 

 projecting toward the end of the jaw, so that each rib resembles quite ex- 

 actly the sign called " brace" by printers. 



