244 GEOL. AND NAT. HIST. SURVEY OF MINNESOTA. 



rows of tubercles. Sometimes a transition from a lined shell to a 

 tuberculate shell is seen (as in Plate LXIII, Fig. 14). Alona tuhermkita 

 Kurz is said to have a truncate and incised post-abdomen with no 

 lateral row of hairs. Birge thinks these identical; if so, our form re- 

 ferred to A. glackdis is identical with A. pio-vula. There is also a form 

 found with the above in which no markings are visible and the shell 

 is considerably arched; these were, however, nearly all ephippia 

 females or approaching that period. 



^'-^ Alona f/JaciaJis (?) var. inhcrcuJata Herri ck (Plate LXIII, Figs. 4-7 

 and 14) will, then, be our tuberculated alona with a lateral row of scales 

 and a series of fine spines along the anus. Alona glacial'ts (?) var. Iwvis 

 Herrick is the smooth form with higher dorsal margin. 



"The antennae of the two last have spines at the end of the rami of 

 the antennae, a circlet of spines on the outside of the second joint of 

 the setose ramus, and a spine on the basal joint of the other ramus; 

 two of the sette at the end of the setose ramus have spines at the 

 angles. The males found among the above small forms have the same 

 characters as var. Icevis and the abdomen is rounded at the end; the 

 claw is situated in the middle of the lower margin, in front being the 

 opening of the j>o/w(.s c/enitali.s and behind a cluster of hairs; the spines 

 are absent, but there is a lateral row of long bristles. A strong hook 

 is found on the first foot. Length 0.3 mm." 



To the above, which expressed my opinion in 1884, I can only add 

 that I am more than ever convinced that all should be united (probably 

 with A. (juttata). 



Alona (lentata P. E. Mueller. 



Plate LXII, Figs. 12, 13. 



Form sub-rectangular, somewhat arched above, obscurely longi- 

 tudinally striated; lower angle obtuse, margined below with short 

 setse. Post-abdomen small, slender, armed with a lateral line of scales 

 and two strong teeth at the lower angle; claw with a minute basal 

 spine. The form of the post-abdomen is identical with Harporhynchus 

 falcntus Sars, which this species also resembles in having the pigment 

 fleck larger than the eye, and in general form and the character of the 

 striation. The beak, however, is very short. In size P. E. Mueller 

 says it is among the smallest of the genus. 



Alona intermedia Sars. 



Plate LXII, Fig. 15. 

 Alona guttata — P. E. Mueller. 



Form sub- rectangular, rounded below; beak short; shell marked 

 by longitudinal lines, which may be broken into indistinct rectangular 



