226 
GEOL. AND NAT. HIST. SURVEY OF MINNESOTA. 
in front and the anus at the end of the post-abdomen. Many eggs are 
produced at once. The male opening is at the base of the abdomen, 
as in Sididw. The general habitus is, however, lynceid. The males 
appear in autumn or when, by the gradual drying up of the water 
or other causes, the continued existence of the animals is threatened. 
GENUS EURYCERCUS Baird. 
Characters of the sub-family. 
Eurycercus lamellatus O. F. Miiller. 
PLATES XLVI, Fies. 7, 8; LI, Fie. 6; LX, Fies. 5, 6; LXII, Fie. 19. 
Lynceus lamellatus — Mueller, Edwards, Koch, Zaddach, Lievin, Leydig, Zenker. 
Eurycercus laticaudatus — Fischer, Schoedler. 
A gigantic Lynceid, reaching the dimension of 3.0 mm. The figure 
of the male given will sufficiently illustrate the general form. The 
abdomen is broad and armed behind with a dense row of saw teeth. 
The eye is larger than the rather small pigment fleck, and the intes- 
tine is bent upon itself but not coiled. The last foot is found in few 
other Lynceide. Acroperus has the same, and Plewroxus unidens also 
has a rudimentary sixth foot. 
SUB-FAMILY LYNCEINE. 
Intestine coiled; anus near the end of the post-abdomen; opening 
of vas deferens nearly terminal. There are no anterior ceca but 
usually a single anal diverticle of the intestine. Rarely or never more 
than two embryos produced at once. 
10 
KEY TO THE SUB-FAMILY LYNCEINE. 
Head or dorsal line keeled or ridged; abdomen long; shell marked with 
diagonal striz. 
Cam ptocercus, 227, 228; Acroperus, 227; Alonopsis, 231 
Usually no keel above, or, if keeled, the post-abdomen is not long. The 
majority are highly arched dorsally, and have comparatively short post- 
abdomen and pointed beak. The antennie are usually feeble and the 
motion slow. 
A. Post-abdomen nearly round in outline, armed with very long, stout 
spines, terminal claw with one minute basal spine or none; greatest 
height of shell about equal to the posterior margin. . Leydigia, 233 
B. Post-abdomen more or less triangular, armed with bristles; greatest 
height of shell moderately exceeding that of the posterior margin; 
shell marked with hexagonal meshes. 
