34 



438 = Cytherea tenuis, Hall & Meek, Mem. Am. Acad. Arts and Sci. 



V, new ser. 383, i, 5. 

 440 = Tellina formosa, Meek & Hayden, Proc. Acad. Nat. Sci. May 



1860, 179. 



454 =; Solen irradians, Roemek, Kreid. Vou. Tex. 1852, 54, vi, 9. 



455 = Psammobia cancellato-sculpta, Roe:mer, ib. 4G, vi, 10. 



473 = CYMELLA, Meek. Type Pholadomya undata. Meek & Hay- 

 den, Proc. Acad. April 1856, 81. 



Shell small, subequilateral, ovate, with numeroias regular, 

 well-defined concentric undulations, crossed on the middle of 

 the valves by a few radiating impressed lines, not marked in 

 the depressions between the ridges. 



480 = Leda fibrosa, Evans & Shdmard, Trans. St. Louis Acad. 1857, 39. 



509 — Not being acquainted with the hinge and interior of this genus, I 

 placed it with doubt in the family Saxicavidx. Since the cata- 

 logue was stereotyped, I have been informed by Prof. Agassiz, 

 that he has specimens showing it to possess the internal 

 characters of the MijtUidx. 



526 = GONIOCHASMA, Meek. Type Xylophaga Stimpsoni, Meek 



& Hayden, Proc. Acad. Phila. May 1857, 141, 



Differs from Martesia in having no accessory dorsal pieces, 

 and in having the anterior hiatus formed by a rectangular 

 notch in the antero-ventral margin of each valve. 



527 = XYLOPHAGELLA, Meek. Type Xylophaga elegantula, 



Meek & Hayden, Proc. Acad. Phila. 1857, 141. 



Has the form and ornamentation of Xylophaga, but internal 

 casts show the impression of an oblique, internal postero-dorsal 

 ridge not seen in that genus. Burrows apparently always 

 withoiit a shelly lining. 

 542 = Ringicula pulchella, Shumakd, Proc. Boston Soc. Nat. Hist. Sept. 

 1861. 



Since the publication of a paper on the Actxonidae, in the Am. 

 Jour. Sci. vol. XXXV, p. 84, I have, through the kindness of 

 Dr. Stimpson, had an opportunity to examine a drawing of the 

 animal of a recent Rintjicula (R. arctata, Gould), made by him 

 from a living specimen taken on the coast of China. From 

 this drawing, and his notes, it appears that it has a large well- 

 developed siphon, which lies (perhaps when the creature 

 moves) folded back upon the body whorl between two short, 

 unequal tentacular lobes ? From this fact, and the general 

 dissimilarity of the animal to any of the known types of the 

 ActcConidsE, I can scarcely doubt the propriety of regarding this 

 genus as the type of a distinct family, which will probably in- 

 clude the extinct groups Rimjinella, Cinulia, Avellana, Euptycha 

 and Aptycha. 



