42 F 
EKWAX RIVER 
Muifeum of the Survey, was collected on the Fawn river, or branch of 
the Severn, by Mr. A. P. I.ow in 188G. 
Camarotachia L'ku’anensis, sp. nov. 
Shell small, moderately convex, transversely subelliptical and wider 
than Ion*?. 
N'eniral valve with an extremely small, narrow, erect or straight 
beak, behind, and a well defined me.sial sinus, that extends backward 
to about the mkllenglh, in front; the whole surface of the A’alve 
marked with thirteen rather distant angular radiating ribs, three in 
the mesial sinus and five on each side. 
Dorsal valve with a still smaller beak, and with a fold corre.sponding 
to the mesial sinus of the ventral, its surface marked with twelve angu- 
lar ribs, four on the fold and four on each skle of it. 
Hinge area and interior of the valves unknown. 
Ekwan river, portage road at falls: one well pre.served cast of the 
interior of the closed valves. 
This small rhynchonelloid may possibly prove to be an extreme 
variety of mylecta (the Airypa iieylecia^ Hall, of the second volume 
of the Palicontology of the State of Xew York) from which it seems 
to differ chiefly in its transver.sely and rather narrowly subelliptical 
marginal outline. 
Atrypa reticularis^ L. 
Ekwan rivei-, foot of portage road : two small specimens. 
Olassit rnrinhilis, sp. nov. 
Shell very .small, strongly compressed and lenticular in outline in 
transverse section, or moderately convex and varying in marginal 
outline from nearly circular and sometimes a little wider than long to 
subovate and a little longer than wide. 
Ventral valve with the front margin either nearly straight and 
devoid of sinus, or faintly sinuated, or provided with a rather wide 
but not di.stinctly defined, .shallowly concave or not very deep, me.sial 
sinus, that extends backward to about the midlength. Umbo of the 
ventral valve small, narrow and not very prominent or produced, its 
beak slightly incurved and apparently perforate. 
Dorsal valve with the umbo and beak smaller than those of the 
ventral. 
