156 INVERTEBRATA OF MASSACHUSETTS. 



FIGURE 5. 



State Coll., No. 265. Soc. Cab., No. 2415. 



Dentalium dentalis, LIN.; Syst. Nat., 1263. BORN; Mus., t. 18, f. 13. MATON 

 and RACKETT; Lin. Trans., viii. 237. DESHAYES ; Mem. de la Soc. d'Hist. 

 Nat., ii. 353, pi. 16, f. 9, 10. LAM. ; An. sans Vert., v. 595. 



Dentalium striatum, MONTAGU ; Test. Brit., 495. 



Dentalium attenuatum, SAY ; Journ. Acad. Nat. Sc., iv. 154, pi. 8, f. 3. 



Shell slender and tapering, curved like an elephant's tusk, the 

 tip cut off, leaving a very small opening. Surface rather glossy, 

 yellowish-white, marked with about twenty closely arranged, un- 

 equal, rib-like striae, running the whole length of the shell. 

 Length about an inch ; diameter at the larger end about i inch. 



I am enabled to add this shell to our list through the kindness of my 

 friend W. W. Wheildon, of Charlestown, who sent me the specimens, 

 accompanied by the following memoranda. 



" Two specimens of Dentalium were taken from the stomachs of cod- 

 fish, in the Spring of 1839. They were both found to have penetrated 

 the entrail of the fish, and were firmly fixed there. They had proba- 

 bly been in the fish for some length of time. Both specimens were 

 unfortunately eroded, one of them so much so that it is quite impossible 

 to determine any of its characters, except its size, its markings being 

 entirely obliterated. In the other specimen the stria? are distinct, and 

 seem to conform to the D. dentdlis of the coast of England. Twenty 

 to twenty-two striae may be counted on its surface." 



FAMILY CALYPTRcEJl, LAM. 



Shell basin-shaped, serving as a cover to the animal ; distinguished from 

 the preceding family by the branchia being situated in a peculiar cavity upon 

 the back. 



GENUS CEM^RIA, LEACH. 



Shell. small, like Patella, with the apex elevated and curved 

 forwards, and with a fissure just behind the apex. 



CEMORIA NOACHINA. 



Shell small, white, conical, covered with unequal, radiating 

 ribs ; apex curved forwards, and perforated obliquely backwards. 



FIGURE 18. 



