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 I. 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 quadeangulaeis, 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, 

 Tostrum 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 seta?, 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. 



