STATE GEOLOGIST. 105 



Daphnia reticulata, Desmar'est, Cons. g6n Crust., 374. 

 M. Edwards, Hist. Nat. Crust., iii., 381. 



Baird, Trans. Berws. Nat. Club, ii., 148. 



Daphnia ventricosa (?) Koch, Deutsch. Crust., h. XXXV., t. 21. 

 Daphnia quadrangula, Midler, Ent., 90, t. 13. f. 4. 



Latreille, Nat. Hist. Const. IV., 227. 



Monoculus quadrangula, Gmelin, Linn. Syst. Nat., 2999, No. 24, 



Monoculus quadrangularis, Manuel, Enc. Mith., VII., 723, No. 15. 



Monoculus quadrangulus, Fabricius, Ent. Syst., ii., 492. 



Xote. — I was not able to fully satisfy myself that this is certainly identical 



with the species described by Baird but there are no good reasons for believing 



it a distinct species. It is round enough for D. rotunda. There is an evident 



spme on the posterior angle of the shell, though it sometimes is almost obsolete. 



The reticulations are hexagonal (?). The color in the specimens examined is 



greenish, and moreover the superior antennae agree better with reticulata than 



rotunda. The size is small. 



Description. — SmaE. (.02 in. or over). Carapace oval and comparatively very 

 broad, covered with hexagonal markings. Head small as compared with the 

 body, and more nearly at right angles with it than in most of the Daphniae. 

 There is also a slight depression a httle in front of the juncture with the body. 

 Superior antense rather larger than in most Daphniae, and somewhat movable. 

 Inferior antennae quite large. Beak none. Feet as in the larger species. 



This species is very active on account of the length of the antennae, which have 

 shorter spines (not plumose) than D. pulex. It presents a robust appearance in 

 swimming either on its back or face, since it is much broader in proportion than 

 most other species. 



Habitat. — Lake Amelia, (rrassy Lake, etc. Not very abundant but widely 

 distributed. 



Baird says of this species: " The ephippium differs considerably from that of 

 pulex. It is more rounded, white at the centre, with a large round ampulla, 

 containing only one ovum. When the animal has the ephippium on, it pos- 

 sesses a square appearance, and is the D. qaadrangula of Muller." 



This is one of the commonest species in many of our lakes, while in others it is 

 replaced by the pulex, for as yet I have not seen them both in the same locality. 

 Habitat. — Grassy Lake, Lake AmeHa, etc, 

 (See Plate VII.) 



Daphnia spinoea, Herrick. 



Description. — General shape of the Daphnia pulex; carapace armed at the 

 upper posterior margin with a rather long, serrated spme. The first of feet are 

 long, bristled at the extremity as in young specimens of D. pulex. The anterior 

 antennae are larger than in pulex and two-jointed and setae-bearing at the end. 

 Posterior antennae exactly as in pulex. The eye is nearer the antennae than in 

 other species, but the most striking peculiarity is the pointed spine formed by 

 the front of the head, which is very marked. Carapace not obviously reticulated, 

 transparent. 



Habitat. — Found in Lake Calhoun, but not in large numbers. It seems to in- 

 habit the deeper waters. 



(See Plate XIII., p. 1.) 



