NASSTDiE. 159 



(Iraiued at low tide. It is found alnindautl}' at the confluence 

 of fresh and salt water, where the taste is merely brackish. No 

 shell of equal size is so abundant on the whole Atlantic shore. 

 The 3'ounger shells are most likely to be collected, because the 

 old ones become very much eroded and defaced, and a greenish 

 mould-like plant vegetates abundantl^^ upon them. Ver^^ few, 

 therefore, of the shells usually collected, have the lines on the 

 interior of the outer lip. The ova-capsules are laid during April 

 and Maj^, are of transparent corneous texture, singly attached to 

 the inside surface of a vah^e of Mactra, or the inner face of the 

 nidus of Natica; they are deposited in vast numbers, completely 

 covering the object to which they are attached and crowded 

 together promiscuously. 



VENASSA, von Martens. Base with a callous spiral deposit 

 encircling the indented umbilicus. N. pulvinaris, von Mart. 

 Timor. 



PTYCHOSAtPiNX, Gill. Shell ovate, buccinoid, whorls regularly 

 rounded and ventricose ; spire moderate (about as long as the 

 aperture), furnished with equal revolving linear ridges, siphonal 

 canal ver}^ short, very obliquely twisted and concurrent with the 

 siphonal fasciole ; aperture rhombo-ovate, oblong ; labrum entire, 

 not sinuous, smooth within ; columella inversely sigmoidal, con- 

 cave near the middle, with a very thin callous deposit and with 

 a revolving linear plait in front. Dr. Gill refers this group to 

 the family Buccinidae, but I agree with the late Mr. Conrad that 

 his description indicates (as do the types cited) Nassee. N. 

 Hcalaitpira^ Conrad (lii, 95). Miocene; Yirginia. 



PARANASSA, Courad. Differs from Ptychosalpinx in the sub- 

 margin of the labrum being slightly thickened within and striate ; 

 siphonal canal shorter. Eocene, Miocene ; America and Europe. 

 N. granifera^ Conr. (lii, 96). Virginia. As one of the two spec- 

 imens of the type of Paranassa is striate within the aperture, 

 while the other is smooth, probabl}^ the distinction from Ptycho- 

 salpinx will not hold good. 



TRiTiARiA, Conrad. Elongated, subturreted, labrum not thick- 

 ened within. This does not seem to differ generically from the 

 true Nassas ; it has very little resemblance to Ptychosalpinx. 

 N. peralta^ Conrad (lii, 91). Miocene ; Virginia. 



Neritula, Plancus. 



Syn. — Cyclops, Montf. Cyclonassa, Swains. Nana, Schum. 

 Cyclocyrtea, Agass. 



Distr. — 3 sp. Mediterranean, Black Sea. N. neritea, Linn, 

 (lii, 98, 99 \ 



Shell ovate, depressed, axis distorted ; spire flattened, oblique, 

 whorls smooth ; aperture depressed ; columella smooth ; inner lip 



