STATE GEOLOGHST. 101 



(19.) Alona g-lacialis ( ?), var. tubercnlata, (Var. n.) 



(Plate G. 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 glacialis (?), var. Isevis, (var. n.) 



is the smooth form^with higher dorsal margin. 



The antennge 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 setas 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. Isevis 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 i^onis genitalis 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 



Sp. 17. Aloua Inteniiedia, Sars. 



(Plate I. Fig. 15.) 

 Alona guttata, p. e. muellee. 



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

 by longitudinal lines, which may be broken into indistinct rec- 

 tangular meshes. Post-abdomen short and wide, rounded at the 

 end, ornamented by clusters of minute spines behind as well as a 

 lateral row of scales. About 0.3 mm. long. 



Section B. Alonella, Sars. 



In this group are included small species with a combination of 

 ■characters, forming the link between Alona and Pleuroxus. An 

 obvious character is the fact that the shell is usually partly marked 

 by oblique striae, which run in two directions: first, a set extending 

 forward and upward from the lower posterior angle of the valves; 

 second, a set springing from the anterior and lower angle, running 

 across the others. At the central part where these two series in- 

 tersect, they each become zigzag; thp result is a series of hexagonal 

 markings, which may extend to the middle of the lower margin. 



The beak is short and the fornices broad; the shell is more or 

 less rectangular, but somewhat elevated in the middle above. 



