62 AMERICAN JOURNAL 



12,) rounded, erect, slightly compressed, witli the anterior 

 and upper surface covered with facettes formed by reticu- 

 lating ridges or ciests, the angles of which are spinous. 



It differs from Nassa and Phos in the form of the oper- 

 culum and the want of candal cirri on the foot. From 

 Nortlda in the shape of the shell, as well as that of the 

 operculum. The typical species is littoral in station, living on 

 mud-flats in bays and harbors, and is found more abundantly 

 than any other gasteropod on the Eastern coasts of the 

 United States of North America. 



Fam. CLIONELLIDaE. 



The genus Clionella of Gray,'"^ founded on the Buccinum 

 smuatum of 'BoYrt=Pleiirotoma buccuwides Lam,f will form 

 the type of a new family. It has been supposed, from the 

 color of the thick periostraca of the shell, to be a fresh-water 

 genus, and is placed in the Melanopsinas by recent authors. 

 It is, however, as has been already pointed out,:|; a marine 

 form. We have had opportunities of observing the living 

 animal in specimens dredged from a sandy bottom at the 

 depth of two fathoms, in Simon's Bay, at the Cape of Good 

 Hope, by the United States North Pacific Exploring Expedi- 

 tion. The soft parts do not accord with the figure of the type 

 given in H. & A. Adams' '' Genera," pi. xxii., f. 10. § 



In our specimens the eyes are placed near the tips of the 

 tentacles; the foot is short and very broad, projecting 

 anteriorly but little beyond the head, and broadly rounded 

 behind. The operculum is subelliptical, with the nucleus near 

 the middle of the inner side, — resembling that of Clavatula,a,s 

 fio-ured by H. &. A. Adams, and that of Tomella, as figured 

 by Gray.f 



"The lingual dentition is of a very peculiar type, differing 

 from any yet described (plate 9, fig. 18.) The animal has a 

 true lingual ribbon, wdth the teeth in three rows 1* 1* 1 ; 

 the rhachidian tooth being very small and delicate, as in 

 Fasciolaria, and armed with a single denticle ; while the lateral 

 teeth are very large, not versatile, and shaped somewhat like 

 the canine teeth of Mammals, pointing obliquely inward and 

 backward, and hollow at the root or base of attachment. 



* Proceedings Zoological Society, London, 1847, p. 153. 



fSee Kiener, Pleurot., p. 38; pi. xiii., f. 1. 



;}: American Journal of Science and Arts, [2J xxxviii., p. 48. 



i^This figure is said to be taken from the " Regne Animal"" of Cuvier, 

 Ed"^ 2d. May not some confusion have arisen between the ideas concerning 

 the animal in question and the Mehinopals buccbwidea, in consequence of 

 the similarity of specific names? We have not the "Regne Animal" at 

 hand to refer to. 



ii Guide, I., p. 7, fig.4. 



