THE NAUTILUS. 77 



of 17 or 18 low, rounded ribs with rather shallow narrower in- 

 terspaces channeled only near the beak; the minor sculpture, if 

 any existed, has been removed by abrasion but there are faint 

 traces of fine radial striae in the interspaces; the hinge has a 

 very large resiliary pit with a narrow ridge on each side of it; 

 the adductor scar was large and the the margins of the valves 

 was undulated by the external sculpture. Height of right 

 valve, 120; width, 125; length of hinge-line, 70; (semi) diam- 

 eter, 28 mm. U. S. Nat. Mus. Cat. No. 333042. 



A fragment has a width of 147 mm. The nearest relative is 

 perhaps the Pliocene P. cerrosensis Gabb, which has twenty-five 

 much stronger ribs with much narrower interspaces, and a less 

 inflated and smaller shell. 



PECTEN (PATINOPECTEN) RHYTIDUS n. sp. 



Right valve very thick and heavy, little inflated, subcircular, 

 with 13 or 14 narrow ribs, here and there subnodulous or 

 slightly imbricated, with much wider flattish shallow inter- 

 spaces; the whole surface is finely radiately striated; there is no 

 minor sculpture except the striation; the hinge-line long, 

 straight, the ears subequal with coarse incremental sculpture; 

 resiliary pit deep and wide, with a strong groove on each side; 

 adductor scar large; valve-margins undulated by the external 

 sculpture. Height of shell, 128; width of shell, 130; of hinge- 

 line, 80; (semi) diameter, 12 mm. U. S. Nat. Mus. Cat. No. 

 333044. 



No species of the late Tertiary or Recent fauna resembles this 

 at all closely. 



THE TYPE LOCALITIES OF LYMNAEA EMARQINATA SAY AND 

 L. AMPLA. MIGHELS. 



BY OLOF O. NYLANDER, CARIBOU, ME. 



In 1821 Thomas Say described Lymnasus emarginatus (Jour. 

 Acad. Nat. Sci., Phila., II, 170) discovered hy Aaron Stone in 

 lakes of Maine. The type is apparently lost and the name of 

 the lakes not given. Walter Wells in his book " The Water- 



