THE NAUTILUS. be 
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, 28mm. 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 18 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, 12mm. 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 EMARGINATA SAY AND 
L. AMPLA MIGHELS. 
BY OLOF 0. NYLANDER, CARIBOU, ME. 
In 1821 Thomas Say described Lymnezus 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- 
