Laguna Warine Laboratorp 117 
than antepenultimate and slightly shorter than last; last two joints 
very heavy and armed with stout spines. Second antenne with 
fourth joint distinctly separated, the outer branch with terminal 
claw longer than claw of inner branch. The tuft of spines on outer 
margin of third joint of inner branch, nearer to apex than base. 
Mandibles at masticatory margin broader than at insertion of pal- 
pus; palpus with respiratory plate not distinctly separated, but its 
three spines are large, recurved and heavily plumose; the terminal 
portion of palpus distinctly one-jointed; one large spine at base of 
palpus. Second leg with basal joint shorter than second, the fourth 
but little longer than third. 
Subclass CLADOCERA 
Chydorus simplex n. sp. 
(Figure 64) 
With Diaptomus stagnalis and Cyprinotus califormicus, Mr. Hall 
took numbers of an exceedingly minute (length .4-.5 mm.) Chydorus. 
The anterior projection of the shell is long, very slender, and very 
sharp, and is frequently more closely incurved to the anterior margin 
of the shell than in the specimen drawn. The shell has a depth about 
three times the hind margin. The distal (lower) margin is edged 
with minute short plumed hairs to a point in front of the legs where 
the curve to the anterior angle begins, and from that point to the 
anterior angle they are replaced by small teeth. The postabdomen 
is long subrectangular, the terminal claws shorter than its greatest 
width and these claws provided with a rather strong lateral tooth 
behind. Lower hind border of postabdomen with a number of small 
tufts of short hairs which are longer distally. Two long spines occur 
above the anal opening. Posterior intestinal eecum long and slender. 
