BRANCHIOPODA. 133 



Here the eyes are sessile and immovable; the body is invested with 

 an oval shell resembling that of a molluscous bivalve, and the ova- 

 ries are always internal. Such is the 



Limnadia, Ad. Brong.(l) 



The Limnadiae are so closely allied to the preceding subgenus, 

 that the only species known was placed among the Daphniae by the 

 younger Hermann. The shell is bivalve, oval, and incloses the body, 

 which is elongated, linear, and inflected forwards. In the head, and 

 almost confounded with it, we find: 1, two eyes closely approxi- 

 mated and placed transversely; 2, four antennae, two of which are 

 much the largest, each composed of a peduncle of eight joints and 

 of two setaceous branches or threads divided into eight segments 

 and somewhat silky; the two others are intermediate, small, simple, 

 and widened at base; 3, the mouth, situated beneath, and consisting 

 of two inflated mandibles arcuated and truncated at the inferior ex- 

 tremity, and of two foliaceous jaws. These parts when united form 

 a sort of inferior rostrum. The body, properly so called, is divided 

 into twenty-three segments, each of which, except the last, bears a 

 pair of branchial feet. All these feet are similar, strongly compress- 

 ed, and bifid; their external division is simple, and ciliated on the 

 exterior edge; the other has four joints, and is strongly ciliated along 

 its interior margin. The first twelve pairs are of equal length, and 

 larger than the others; the length of the latter progressively dimi- 

 nishes. The eleventh pair, and the two following ones, have a slen- 

 der thread at their base, which ascends into the cavity situated be- 

 tween the back and the shell, in order to support the ova. The last 

 segment on the tail is terminated by two threads. The ovaries are 

 internal, and placed along the sides of the intestinal canal, extending 

 from the base of the first pair of feet to the eighteenth; their open- 

 ings appear to be at the root of some of those that are intermediate: 

 The eggs, after having been produced, occupy the dorsal cavity 

 above mentioned, and are secured there by means of small threads, 

 which adhere to those of the feet. At first they are round and trans- 

 parent; they afterwards assume a yellowish tint, which is subse- 

 quently darker towards the centre, and their figure becomes irregu- 

 lar and angular. 



All the individuals examined by M. Ad. Brongniart were provided 

 with them. The males, allowing the sex to exist, do not appear at 



(1) In my work on the natural families of the animal kingdom, this subgenus, 

 with that ofJlpus, composes my family of the Aspidiphora; it approximates to this 

 one in the number of feet, and to the Daphnise in the shell. 



