22 TWELFTH ANNUAL REPORT. 



reflexed, reaching base of shell ; anterior antennae extremely long; 

 copulating organs reaching nearly to end of claws. Having care- 

 fully compared our specimens with the descriptions and figures 

 given by Birge for his D. expinosa, the evidence seems to indicate 

 not only that they are identical, but both are really D. brachyura* 

 The distinctive characters of D. expinosa are a greater indentation 

 between head and body, absence of caudal teeth, greater length of 

 male appendages, and the opening of the vasa deferentia below the 

 *' instep " of these appendages. 



The absence of teeth upon the post-abdomen is of even generic 

 importance according to Sars, who gives it in his synopsis of 

 genera as typical for Daphnella, In our specimens the claws are 

 at least pectinate if not serrate, while the appendages of the male 

 reach generally nearly to the middle of the claws. The relative 

 length of these appendages and the antennae of the male is variable^ 



Sp. 2. Daphuella brandtiana, Fischer. 



Head as long as half the body, antennae when reflexed reaching 

 beyond the posterior margin of the valves. Length 0.8 mm. Of 

 the validity of this species we can form no conclusion. It is 

 usually considered a variety or phase of the above. 



V. — Genus Latona, Straus. 

 (Plate K. Fig. 8.) 



Body elongate, broad; head large and square, appendaged below 

 with triangular laminae ; fornices present. Antennules rather 

 large. The larger ramus of the antennae is two-jointed and has an 

 expanded process at the base. The lower posterior angle of the 

 shell has a peculiar diverging set of setae. The shell is often orna- 

 mented with numerous flecks of bright color. There is a copula- 

 tory apparatus in the male. 



Latona setifera, Mueller, 



Is the only species, and is not yet recognized in Minnesota, but 

 was found by Prof. Birge in lake Michigan. 



FAMILY HOLOPEDID^. 



Genus Holopedium, Zaddach. 

 (Plate N. Pig. 11.) 



The peculiar animal bearing the name Holopedium gibberum 

 has the brood cavity greatly elevated, and the whole upper part of 



