108 ANNUAL EEPORT. 



Description. — Carapace ovate quadrangular, but somewhat variable, being in 

 some specimens quite abruptly rounded on the posterior margin, while in others 

 it is almost truncate; shell of a yellowish or brown color, heavily marked and 

 ciliated below. Beak blunt, varying in position in different individuals. Abdo- 

 men flat, sinuated at the extremity and bearing long claws. Anterior antennae 

 of moderate size. Eye rather large. Larger anbennse rather long. 



Total length between .03 and .04 in. This species is also quite abundant, 

 and if I am right in referring it to the L. quadrangularis of Muller, is quite vari- 

 able. Drawings made from individuals collected at different localites on com- 

 parison show minute differences of form and markings. The intestine is strongly 

 convoluted in this species, but the dark color of the shell usually interferes \5p.th 

 observations of the organs within. 



Plate XY. fig. 2. 



Lynceus sphaericus, Muller. (?) 



Bibliographij . — Lynceus sphsericus, Muller. 



Latreille. 



Lamarck, 



Desmarest. 



Baird. 



M. Edwards. 



Prichard. 



-Koch. 



Monoculus sphsericus, Gmelin. 



Manuel. 



Fabricius. 



Jurin e . 



Monoculus infusorius, Schrank. 

 Eichorn, 



Chydorus Mulleri, Leach. 



Chydorus sphaericus, Baird, Ann. and Mag. Nat. Hist. ii. 89, t. 2; 

 Brit. Entomst. p. 126. 



Description. — Baird's description of this species is applicable to any one of 

 several almost equally, and the only recourse seems to be a reliance on the figure 

 he gives with which our species seems to correspond quite well. 



The shell is round and nearly blunt behind, the antennae are quite small, so 

 that the animal rolls slowly along like a corpulent sailor on land. Not enough 

 attention has been devoted to this and the following species of the genus. 

 Length, .03 in. Plate XIII, fig. 2. 



Lynceus sp,? 



See L. (Pleurus) trigonellus, P. uncinatus etc. of Baird, 



The animal figured in Plate XII, Fig. 3, evidently belongs to the genus Pleu- 

 roxus of Baird. In examining several specimens the turned up beak was 

 found in several cases while in others it was seen as represented at (3a) of the 

 same plate. Dr. Baird separated two species on the ground of this variation, 

 but it does not seem to be a specific character. The length is ,03 in. in the 

 species seen, and except that the shell is longer in proportion, agrees prettj well 

 with L. trigonellus, Muller. 



