CAMBARUS. 1S 
and the inferior median anterior spines of the carpus are well developed ; 
of the spines of the meros, the superior apical and the external row of the 
inferior biserial ones are developed; only one or two of the distal ones of 
the inner row are present. In one specimen the fingers are much elongated. 
There is a dark rmg around the fingers near the tip. The carapace is 
flattened above, densely and coarsely punctate, lateral spines small, acute ; 
areola as wide as in the typical @. rusticus, and of a similar form. <A closely 
similar form comes from Lizard Creek, Fort Dodge, Iowa (M. C. Z., No. 3554). 
In small specimens, 52 mm. long, males of the second form and females, 
from Southern Indiana (M. C. Z., No. 5555), the lateral spine of the carapace, 
the anterior spine of the post-orbital ridge, and the spine of the carpus and 
meros, are acute and well formed, though small. The rostrum is excavated, 
and thickened on the margins, as in the typical C. rusticus. 
A type, male form IL, of C. Wisconstnensis Bundy, from Racine, Wis., re- 
ceived from Dr. Bundy (M. C. Z., No. 5448), agrees in most particulars with 
C. placidus Hagen. The rostrum is shorter, and the internal part of the 
first abdominal appendages is swollen near the tip, as in Hagen’s C. rusticus. 
The anterior process of the epistoma is not truncate or emarginate. The 
interior median and inferior median carpal spines are well developed. 
In the same jar with C. virilis from the Osage River (M. C. Z., No. 169) 
I find many small specimens, males of the second form and females, which 
agree very closely with the types of C. placidus from Lebanon, Tenn., and 
from Texas. With these goes a single first-form male from the same local- 
ity (Osage River), determined by Hagen as @. juvenilis (M. C. Z., No, 271). 
The largest of these specimens (a female) is 71mm. long. The rostrum 
and antennal scale are as in C. placidus, the fingers of moderate length, the 
internal median carpal spine well developed, the inferior median carpal spine 
small and acute (in the first-form male obsolescent), the areola narrow. ‘The 
first abdominal appendages of the first form of the male have a prominent 
angle on the anterior border, the inner ramus is straight, dilated at the tip, 
the outer ramus is a little recurved ; in the second form of the male the inner 
ramus is straight, the outer slightly recurved at the tip. The imer side of 
the base of the external finger is bearded in the female and second-form male, 
naked in the first-form male. Differs from C. Pufnami m having a narrower, 
more excavated rostrum, narrower areola, and shorter male appendages. 
In the collections of the Peabody Academy of Science, the Boston Soci- 
ety of Natural History, and Bowdoin College, there are many young speci- 
15 
