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



* Dapliina exilis sp. n.? 

 Plate LII, Figs. 4, 5. 



It is admittedly undesirable to describe a specimen instead of a 

 species, but the form for which the above name is provisionally pro- 

 posed is so peculiar and its locality so little studied that a description 

 is given based on a single young female. It will be understood that 

 the ovigerous female would differ in the length and position of th& 

 spine, size of crest and form of the abdominal processes. 



A daphnid of moderate size with crested head, long spine and den- 

 tate caudal claw. Nearly colorless. Head projecting in the line of 

 the axis of the body, crested from the eye to a point cephalad of the 

 heart, but truncate in front. Ventral outline nearly straight, beak 

 not projecting, antennules very short and applied almost at the end 

 of the beak, which does not lie between the valves. Eye of rather 

 large size, with few crystallines, near the ventral margin. Pigment 

 fleck small, nearer to the caudal margin of the head than to the eye. 

 Coeca narrow, strongly curved. Antennte short and stout, second 

 segment of the set?e longer than the basal. Fornix moderate. Valves 

 sub-oval, strongly curved ventrally, dorsal outline straight from in 

 front of the heart to the spine, which is very long and curved dorsad. 

 In this specimen the spine is longer than the entire valve. There is 

 no dorsal emargination between the head and body Dorsal margin 

 armed with spines beyond the heart, ventral margin spined more than 

 half of the length. Valves marked with the usual quadrangular 

 meshes. Post-abdomen narrowed toward the end. Anal margin sin- 

 uate. Anal teeth about eight, nearly equal. Claw short and moder- 

 ately curved, armed with a continuous series of spinules and a comb 

 of fine spines near the base. Length, exclusive of spine, 1.15 mm.; 

 length of head 0.38 mm., height of head 0.54 mm., height of shell 0.65 

 mm., length of spine 0.84 mm., diameter of eye 0.10 mm, length of 

 base of antennre 0.26 mm., claw 0.09 mm. The abdominal processes 

 in this specimen are not in their mature form. It is not certain that 

 the dense hairiness of the anal margin above the teeth is an adult 

 character. It would appear that the crest is normally a strongly pro- 

 jecting cephalic helmet, but this is but conjectural. Found in weedy 

 pools fed by irrigation canals at Albuquerque. 



* Dapliaia arcuata Forbes. 



Forbes '93. 



''Head helmeted, rounded in front, length one-third that of the 

 shell, front concave, beak produced, extending beyond the sensory 

 hairs of the antennae. Eye small, about midM^ay between the mandi- 



