28 
Guide to Crustacea. 
Table-case 
No. 1. 
(Fig. 9). Leptodora ldndtii is the largest species of the Order. It 
is found chiefly in lakes, and its glassy transparency makes it a 
very beautiful object when alive. It is exceptional in the small 
size of the carapace, which does not enclose the body and serves 
only as a brood-pouch. 
Daphnia pulex. Female carrying eggs in the brood-chamber. 
Enlarged. [Table-case No. 1.] 
Sub-class II — OSTRACODA. 
The number of somites, as indicated by the appendages, is 
smaller than in any other Crustacea, there being, at most, only 
two pairs of trunk-limbs behind those belonging to the head- 
region. The carapace forms a bivalved shell completely enclosing 
the body and limbs. There is a large, and often leg-like, palp on 
the mandible. The antennules and antennae are used for creep- 
ing or swimming. 
