674 FRESH-WATER BIOLOGY 



67 (70) Umbones one-sixth length of shell from anterior end 68 



68 (69) Shell large (16 mm. long), flat; umbones small; flagella of second 



antenna 13- and 15-segmented. 



Estheria californica Packard 1874. 



Thus far this species has been collected at two 

 localities in Cahfornia. The small size of the umbones 

 is remarkable. Length of shell, i6 mm.; height, 

 10 mm ; breadth, 4 mm. 



Fig. 1044. Estheria californica. Shell, side view. X 3- 

 (After Packard.) 



69 (68) Like Estheria californica but umbones more prominent and dorsal 

 edge of shell sloping down to posterior end. 



Estheria newcomhii Baird 1866, 



Possibly the same as the last species but as Packard's and 

 Baird's figures appear to differ somewhat the two are separated. 

 It is found only in California. 



Fig. 1045. Estheria newcombii. Shell, side view. X 2. (After Eaird.) 



70(67) Umbones more than one-sixth length of shell from anterior end. . 71 



71 (72) Shell long and narrow; umbones small, one-fifth length of shell from 

 anterior end; telson armed with small fine teeth; hands of 

 male short and thick; flagella of second antenna 15- and 

 14-segmented. . . . Estheria compleximanus Packard 1877. 



Packard reported this species from two localities in 

 Kansas and more recently Richard discovered it in a 

 collection from Lower California. Length of shell, 

 II mm.; height, 5.5 mm. 



Fig. 1046. Estheria compleximanus. Shell, side view. 

 X 3. (After Packard.) 



72 (71) Shell more or less swollen or globose; umbones prominent. 



73 



73 (74) Shell globose, wider than high; umbones prominent and oblique 



one-fourth length of shell from anterior end, Hues of growth 



not sharply marked Esfheria digiieti Richard 1895. 



Described from Lower California. 



74 (73) Lines of growth well marked; shell not wider than high 75 



75(78) Flagellaof second antennae 15- and 14-segmented 76 



76 (77) Shell globose with 24 lines of growth; umbones large and prominent, 

 two-fifths length of shell from anterior end. 



Estheria helfragei Packard 187 1. 



This fine species was described by Packard from specimens collected 

 in the month of April at Waco, Texas. 

 Fig. 1047. Estheria helfragei. Shell, side view. X 4- (After Packard.) 



