113 



Strong rounded ribs, broader anteriorly, but narrower posteriorly, 

 than their interspaces, not projecting sharply beyond the outline 

 of the shell, but giving it a waved appearance. Long. 1 ; lat. 

 .025 poll. Hah. Buzzard's Bay. 



Mr. Stimpson also read descriptions of several new spe- 

 cies of shells from the northern coast of New England. 



Leda obesa. T. parva, tenuis, ovalis, insequilateralis, postice 

 longior, epidermide nitido, tenuistriato ; apicibus parvis ; margine 

 ventrali arcuato : areola parum conspicua; dentibus anticis de- 

 cern, posticis duodecim, parvis. Long. .22 : lat. .12 poll. 



Teredo dilatata. Valves white, polished ; length and height 

 equal ; anterior area with fine, concentric, somewhat diver- 

 gent striae, varying in number in different specimens, and more 

 crowded below ; the slightly oblique lines on the succeeding nar- 

 row area are very minute but sharp ; the next, fang shaped area, 

 is ornamented with distant, narrow, elevated, subimbricated, con- 

 centric lines, more conspicuous on the anterior than on the pos- 

 terior half of the area ; the remaining portion of the body and 

 the auricle are smooth and glossy. The auricle is not separated 

 from the body by any sharp angle on the posterior ventral out- 

 line, but by a gently waved sinus. A depressed line runs from 

 the beak around to the tips of the auricle, which does not tower 

 above the callosities of the hinge. The sub-umbonal blade is thin, 

 tapering, and extends to about half the distance from the beak to 

 the ventral edge. The pallets are of an angular ovate form, 

 truncated posteriorly, where also, on the external surface there 

 is a small depressed area. The style of insertion is sharp and ex- 

 tends in the form of a ridge for some distance on both sides after 

 its juncture with the pallet. The tubes are very thin, strongly 

 concamerated posteriorly in an imbricated manner. This spe- 

 cies differs from T. megatara, Hanley, which it greatly resembles, 

 in the smaller altitude of the valves, the greater breadth of the 

 auricle, which is also placed much lower, and in its concamerated 

 tubes. Length of valves nearly one half of an inch. For many 

 living specimens of this species, I am indebted to Mr. S. Tufts of 

 Lynn, (Mass.) who obtained them from a pine buoy used to indi- 

 cate the position of the lobster pots of the fishermen. Thus there 



PROCEEDINGS B. S. N. H. 8 DECEMBER, 1851. 



