RANDOM NOTES ON NATURAL HISTORY. 



The Shell - Bearing Mollusca of Rhode 

 Island. 



[BY HORACE F. CARPENTER.] 



Chapter VIII. 



Sub-genus Tritia, Risso. 



Spire elevated, whorls reticulated ; inner 

 lip smooth with a moderate callus ; outer 

 lip simple. 



11. Nassa (Tritia) trivittata, Sat. 



Shell ovate-conic, turreted, apex acute, 

 color greenish, reddish, or yellowish white, 

 surface reticulated b}' veiy elevated decus- 

 sating lines ; whorls seven, flattened above 

 so that thej' appear shouldered at the 

 suture ; aperture oval, a few elevated lines 

 within, not reaching to the margin ; outer 

 lip sharp, but scalloped on the edge b}' the 

 revolving lines ; inner lip arched and cal- 

 luesd ; operculum horny, irregularly trian- 

 gular in shape, with one half its edge sharpl}' 

 serrated. Animal whitish with lilac spots. 



The specific name was evidentl}' given b}^ 

 Say on account of the three rufous bands 

 on the body whorl ; these bands are not 

 always present, but Say's specimens were 

 from the Southern States, where it reaches 

 its perfection : our shells sometimes have 

 these bands, but not as a rule. It ranges 

 from Georgia to Halifax, and consequently 

 is subject to much variety in form and color. 

 Specimens from Nantucket have the inner 

 margin heavily coated with enamel, while 

 those from Boston have none. In some 

 cases the longitudinal and transverse lines 

 are of equal distance from each other ; in 

 others the longitudinal lines are more 

 distant, thus giving the shell a different 

 appearance. Most specimens from our 

 northern shores are covered with a greenish 

 black coating while alive, and on the other 

 hand we occasional!}' find one with all the 

 revolving lines colored reddish. It is found 

 in sand from low water mark to fifteen 

 fathoms. It is veiy active and comes out 

 of the sand in a minute or two after the 

 water passes over it. At Nayatt Point is a 

 reef of rocks extending from the light-house 

 out into the bay ; there is always more or 

 less surf at this point, and just within the 



reef, on the side towards Warren, is a low 

 sandy flat, where probably an abundance of 

 this species inhabit, for at low tide can be 

 found quantities of dead shells among the 

 rocks, where the}' must have been driven in 

 by the surf, from their habitat in the 

 sand. They attain a length of four-fifths of 

 an inch by three-tenths in breadth. 



Sub-genus Ilyanassa, Stimpson. 

 Shell dark olive-brown, reticulated ; outer 

 lip without varix, striate within ; inner lip 

 covered with a spreading callus. Opercu- 

 lum with entire margin. 



12. Nassa (Ilyanassa) obsoleta. Say. 



Shell ovate, inelegant, dark reddish to 

 black ; whorls six, covered with a net work 

 of Unes reticulating the surface ; apex 

 obtuse ; aperture oval ; outer lip simple and 

 sharp ; inner lip deeply arched and over- 

 spread with enamel ; interior of the aperture 

 dark purple ; canal, a mere notch ; opercu- 

 lum horn}'. Length one inch, breadth one 

 half inch. 



This shell is one of the most common 

 objects which meet the eye of the visitor to 

 the shore. One can hardly help noticing 

 thousands of them in every direction. It 

 inhabits from Maine to Florida ; it accommo- 

 dates itself to all conditions ; it lives at 

 Block Island, where the ocean washes over 

 them its saline waters ; it thrives equally as 

 well in brackish water, where fresh water 

 streams are met by the inflowing tide ; we 

 find it at high-water mark, on the flats left 

 bare between tides, and at the bottom of the 

 bay and ocean. 



Although we have at all times millions of 

 specimens to select from, a collector might 

 search all day and not find a dozen worth 

 saving. It is very rare, in Rhode Island at 

 least, to find one of these shells (adult), 

 having the decussating lines, together with 

 a perfect apex ; nearly every one is badl}'- 

 eroded, the lines obliterated, and the apex 

 decollated. A greenish, mould-like coating, 

 collects upon them and renders them un- 

 sightly objects. I have some specimens, 

 collected near the Charlestown Navy-yard, 

 which are nearer perfect than any I have 

 seen in Rhode Island. 



The visitor to the shore in search of 

 health or pleasure, may not be aware that 

 it is due to the presence of these insignifi- 

 cant objects, seen on every side in such 



