306 REPORT OP^OMMISSIONER OF FISH AND FISHERIES. 



XXIV, fig. 152.) This species is more at home at the depth of a few 

 fathoms, among algfe. Another still smaller and lighter colored species, 

 Tvhich often occurs abundantly in similar situations, both on algte 

 and under stones, is the Rissoa acutcns, (Plate XXIV, fig. 141,) but this 

 generally seeks more sheltered situations. All these shells feed upon 

 the algaj. With them there can usually be found large numbers of sev- 

 eral carnivorous species. The most abundant one is a small but pretty 

 shell, having a smooth surface and quite variable in color, though usually 

 reddish or purplish brown, and irregularly mottled or banded with yel- 

 lowish or whitish, the light-colored spots often takiug the form of cres- 

 cents, and varying much in size and number. This is the Astyris lunata, 

 (Plate XXI, fig. 110.) It lives among the alga.^ and also among 

 hydroids, and may be found in almost all kinds of localities, both above 

 and below low-water mark. It is usually abundant ou the under sides 

 of rocks among hydroids, &c., and can nearly always be found in 

 the tide-pools. Another allied species of larger size, and much less 

 common, the Anaclils arara, (Plate XXI, fig. 109,) often occurs with it. 

 Clinging to the rocks, or sheltered in the crevices and on their under sur- 

 faces, a much larger, dull-white or grayish, roughly-sculptured shell can 

 usually be found in abundance. This is the Urosalpinx cinerea, (Plate 

 XXI, fig. 110,) which the oystermen call " the drill," a name very suggest- 

 ive of its habits, for it gets its living, like many other similar univalve 

 shells, by drilling a round hole, by means of the sharp, flinty teeth that 

 cover its tongue, through the shells of oysters and other bivalves and 

 then sucking out the contents at its leisure. It is usually very abun- 

 dant on the oyster-beds, and often proves very destructive. Another 

 shell of about the same size, somewhat resembling the last, and having 

 similar habits, is often found associated with it on the more exposed 

 rocky points, as at Xobska Point, the Wepecket Islands, &c. This is, 

 however, a very northern and arctic shell, which extends also around 

 the northern coasts of Europe, and is called Purpura lapillus, (Plate 

 XXI, figs. 118 and 119 ;) it is here near its southernmost limits, for it 

 is not not found in Long Island Sound or farther south ; while the former 

 is a southern shell, abundant on the whole southern coast as far as the 

 Gulf of Mexico, and rare north of Cape Cod, except in a few special 

 localities of sheltered and warm waters. The Purpura is seldom found 

 living much below low- water mark, and prefers the exposed rocky head- 

 lands on the ocean shores, where it flourishes in defiance of the break- 

 ers. It lays its eggs in smooth, vase-shaped capsules, attached to the 

 sides or under surfaces of stones by a short stalk, and usually arranged 

 in groups, (Plate XXI, fig. 120.) The eggs of " the drill " are laid in 

 similar places, but the capsules have very short stalks, or are almost 

 sessile, and are compressed, with an ovate outline, and angular ridges 

 pass down their sides. The " limpet," another northern and European 

 shell, having a low conical form, is occasionally found clinging to the 

 rocks at low-water in this region, but is far more common north of 



