OF DENISON UNIVERSITY. 



39 



the family and has been seen but few times. First described and 

 figured by Fischer, from Russia, it next turns up in Scandinavia, where 

 Sars gives a full Latin description. Norman and Brady find it in 

 England, and Mueller in Denmark, and, finally, Heilich records it in 

 Bohemia. It was also reported from Minnesota, by the writer, 

 in 1884. 



Unlike most other limicole cladocera, the body is narrow and high, 

 rather than globose, the head is much depressed and terminates in a 

 slender rounded beak, like the bill of a duck. The fornices or free 

 margins of the head-shield are narrow and flaring. The shell of an 

 old individual is a curious pile of overlapping valves, and is ornament- 

 ed with concentric series of depressions. The lower margin is nearly 

 straight and bears a row of long curved teeth (not free spines), back 

 of which are two small teeth. The antennae are short and the an- 

 tennules rather slender. In this respect our specimen seemed to dis- 

 agree with the figure given by Heilich. The labrum is of large size 

 and is produced into an acute appendage below, as in most Lynceids. 

 The compound eye is quite absent, but its function is subserved by the 

 larval organ, a quadrate and rather large fleck at the base of the an- 

 tennules. The intestine is coiled once and ime-half times and opens 

 in about the middle of the flat, pentagonal post-abdomen. The latter 

 bears straight terminal claws, each with a single basal spine, a series of 

 rather small triangular teeth, posteriorly, and irregular areas of fine 

 spines upon the sides. The male is not known and many points of 

 interest remain to be made out. 



The two species of Leydigia, both of which occur in America, are 

 familiar enough and are sufficiently well described to render a repeti- 

 tion of the description needless. It is otherwise with the only species 

 of llyocriptus yet found in America. 



Ilyocryptus setifer, Herrick. — The description given in my 

 "Final Report, etc.," is very brief and no comparisons were there 

 instituted with the /. agilis of Kurz which is its nearest ally in 

 Europe. The paper by Kurz referred to gives detailed descriptions of 

 the three European species accompanied by elegant plates. We are 

 able, therefore, to draw up the following distinctive diagnosis of the 

 species, hoping thereby and by means of the figures to show the rela- 

 tions of the four species at present known. It is almost certain that 

 we have more than one species in America and the careful description 

 of the known form may make the detection of others easier. 



