List of Crustacea Cladocera from Madison , Wis. 
393 
very small teeth near the terminal claw. There are 3-4 denticles on each 
side of the anus. This armature of the post-abdomen distinguishes the 
species at once from Ilyocryptus sordidus and I. acutifrons , while the 
antennary setae distinguish it from J. agilis. The fact that moulting is 
imperfect also serves to distinguish it from the latter species. 
This is the common form of Ilyocryptus here, and is very abundant in 
shallow water and marshy localities throughout the summer and until 
after the formation of ice in the winter. The failure of food consequent 
on long continued cold seems the only thing which checks their multi¬ 
plication. Whether I. spinifer , Herrick (op. cit., p. 77), is identical with 
this species can not be decided as none of the specific characters are 
mentioned or figured. 
Species 37. Leydigia quadrangularis, Leyd. 
The shell-markings in my specimens are far more distinct than those 
described by European authors. Otherwise the species agrees entirely 
with the descriptions. 
Species 40. Alona lineata, Fischer. 
If, following Matile’s * advice, the specific name lineata is abandoned, 
my form would be A.pulchra, Hellich. 
Species 44. Alona lepida, sp. nov. Plate XIII. Fig. 19. 
Length, .8 mm. Length of male, .6 mm. 
Height, .45-50 mm. Height of male, .3 mm. 
Length post-abdomen, .40 mm. 
General shape conforms to the normal Alona type. Head depressed, 
rostrum sub-acute, nearly reaching the level of the ventral margin of the 
shell. Valves quadrangular, dorsal margin arched, superior posteal 
angle obtuse, well-marked. Posterior margin oblique, bearing a row of 
minute spinules. Inferior posteal angle rounded, very slightly emargi- 
nate. Ventral margin beset with a row of plumose setae, of ordinary 
length, which ends abruptly at the posteal angle. Valves marked by 
close-set, conspicuous, longitudinal striae, alternately stronger and 
weaker, occasionally anastomosing, running parallel to the dorsal and 
ventral margins and converging into a reticulated area at the anterior 
inferior portion of the valves. Between the striae lie the braces. 
Antennule extends nearly to end of rostrum: is spindle-shaped, largest 
near base, provided with an anterior sense-bristle and 6-8 subequal 
sense-hairs. Antennary setae fff. The terminal setae are of unequal 
length. All are plumose and without spines. The eighth setae is of 
moderate size, bi-articulate and plumose. Spines of antennae, On the 
middle joint of the inner branch is a circlet of small spines. Ventral 
margin of labrum often notched just anterior to the posterior angle, 
* Matile, P. Die Cladoceren der Umgegend von Moskau, 1890, p. 46. 
