156 NASSID^. 



a callosity at hind-part ; outer lip grooved internally, externally 

 niarginated. B. truncata, Rve. (Hi, t6). 



MOLOPOPHORUS, Gabb. Short, robust, spire moderately elevated, 

 suture bordered by a more or less distinct carina. Surface 

 longitudinally ribbed or striate. Aperture obtuse behind, and 

 very slightly notched ; outer lip simple, inner lip very slightly 

 incrusted, sinuous, anterior notch small, but distinctly defined. 

 B. striata, Gahh (lii, 80). Cretaceous; California. 



[bulliopsis, Conr. Placed hj its author at first as a subgenus 

 of Nassa, it was subsequently removed by him to Melanopsidse. 

 It has some resemblance to Bullia.] 



Nassa, Lam. 



Distr. — 131 sp., of world-wide distribution. Fossil, numerous 

 species. Eocene — . N. mutabilis. Linn, (lii, 81). 



Shell ovate, ventricose, body-whorl variously sculptured ; 

 aperture ovate, with a short, reflected, truncated, anterior canal ; 

 inner lip smooth, often widely spread over with enamel, with a 

 posterior callosity or blunt dentiform plait ; outer lip dentated, 

 internally crenulated. Margin of operculum serrated or entire. 



The animal of Nassa has a broad head, and a foot quadrately 

 expanded in front, with the corners often pointed, whilst behind 

 it bifurcates and is prolonged frequently into two subulate tails. 

 The operculum is usually serrate on the margin, but is sometimes 

 plain. The Nass^e are very active, and not at all shy when kept 

 in confinement. They may be occasionally seen floating with 

 the foot upwards. They are predaceous, feeding on other mol- 

 lusks, the shells of which they bore. I have frequently seen the 

 shells of the American species themselves bored, the hole being 

 of such a size as to suggest cannibalism. Perhaps the avenger 

 of their misdeeds is a beautiful and very active hermit crab 

 which disports itself in the Nassa's shell, immense multitudes 

 being seen at low tide in the water near the shore-line. Whether 

 begged, borrowed, stolen, or lawfuHy captured by the red right 

 claw, it is certain that, at Atlantic City, New Jersey, the hermit 

 inhabits a vast majorit}^ of the specimens of Nassa occurring to 

 the collector. Although most of the species are littoral, a few 

 have been collected at considerable depths ; N. hrychia, Watson, 

 was dredged at 620 fathoms b}^ the " Challenger Expedition." 

 Some of them have been observed to spring up and throw them- 

 selves over on being suddenly disturbed. Usually they glide 

 along the surface of the mud, leaving a track indicating their 

 line of march, at the end of which is a small round pellet ; under 

 this the creature conceals itself. The frj^ twist and twirl about 

 by means of their ciliated lobes. N. mutahilis is an article of 

 food in Italy. The generic name is that of a narrow-necked 

 wicker basket used for catching fish, and in such a basket, lob- 



