BRANCHIOPODA. 123 



than the body, setaceous, composed of from seven to eight joints, 

 the last of which are shortest and terminated by a bundle of twelve 

 or fifteen setse, serving as fins. The mouth consists of a carinated 

 labrum, two large dentated mandibles, each furnished with a tri- 

 articulated palpus, to the first segment of which adheres a small 

 branchial leaf with five digitations(l), and of two pairs of jaws. The 

 two superior are much the largest, and have four movable and 

 silky appendages on their internal margin, and a large, pectinated, 

 branchial lamina on their anterior edge; the second are composed of 

 two joints, with a short, nearly conical, inarticulated palpus(2) 

 silky at the end, as is the extremity of the jaws themselves. A sort 

 of compressed sternum fulfils the functions of a lower lip(3). The 

 feet are divided into five joints, the third representing the femur, 

 and the last the tarsus. The two anterior feet, inserted under the 

 antennae, are much shorter than the others, incline forwards, and 

 are furnished with rigid setae, or long hooks united in a bundle at 

 the extremity of the last joints. They are deficient in the four fol- 

 lowing feet. The second, situated in the middle of the under part 

 of the body and at first directed backwards, are arcuated and termi- 

 nated by a long and strong hook inclining forwards. The two last 

 are never visible externally, but are turned up, applied to the poste- 

 rior sides of the body in order to support the ovaries, and terminate 

 in two very small hooks(4). The body presents no distinct articu- 

 lation, and terminates posteriorly in a kind of soft tail which is 

 doubled underneath, with two conical or setaceous threads furnished 

 with three setae or hooks at the end, directed backwards and issu- 

 ing from the shell. The ovaries constitute two large, simple and 

 conical vessels forming a cul-de-sac at their origin, and situated on 

 the posterior sides of the body, underneath the shell, and opening, 

 side by side, in the anterior portion of the abdomen where the canal 

 formed by the tail establishes a communication between them. The 

 ova are spherical. These Crustacea spawn, and change their skin, 

 as frequently as the Cyclopes and other Entomostraca, and their 

 mode of life is the same. LedermuUer states, that he observed them 

 in coitu. Modern naturalists, who have most closely studied them, 

 however, have never been able to discover their sexual organs with 

 certainty, nor been fortunate enough to see them in actu. M. Straus 



CI) Interior lip, Randohr. 



(2) Forked in the Cypris sirigata. Id. 



(3) Exterior lip, Id. 



(4) In the figure given by Randohr these feet consist of but three joints, and the 

 last is somewhat dilated and emarginated at the end, with a hook in the middle of 

 the emargination. 



