branChiopoda. 257 



facility on tlunr back, and their foot, Avliich tliey cannot use for 

 walking, while thus employt^d, ^jresent a graceful and undulating 

 motion. This motion creates a current between them, wliich, follow- 

 ing the canal of the thorax, directs to its mouth the atoms which con- 

 stitute its food ; when the animal wishes to advance it strikes the 

 water, right and left, with its tail, which forces it forwards by 

 bounds and leaps. Withdrawn from its element, it moves its tail for 

 a while, and curves itself into a circle. Deprived of a certain degree 

 of humidity, it remains motionless. 



Benedict Prevost states, that when the male of the species which 

 constitutes the object of his memoir seeks his female, he swims 

 roxmd her, seizes her by the neck with the two horn-like appendages 

 of his head, and remains fixed there, until she turns up the posterior 

 extremity of her tale, in order to ajiproximate the two valves of the 

 copulating organs ; this process is analogous to the coitus of the Li- 

 bellulse. The ova are yellowish, spherical at first, and afterwards 

 angular; the shell is thick and hard, a circumstance which tends to 

 preserve them. It appears that even desiccation, provided it be not 

 carried to far, produces no change in the germ, and that the young 

 are hatched as soon as a sufficiency of rain has fallen. M. Desmarest 

 has frequently remarked Branchipi in the little hollows filled with 

 rain water, on the summit of the rocks at Fontainebleau. The female 

 Chirocephalus produces several distinct sets of eggs, after each copu- 

 lation, at different times, occupying some hours, and even the whole 

 day in the process. Each set consists of from one to four hundred 

 eggs ; they are rapidly ejected from the female in jets of ten or a 

 dozen, and with sufficient force to sink them slightly in the mud. 



Benedict Prevost has remarked that the Chir. diaphanus was sub- 

 ject to certain diseases, of which he gives a description. This spe- 

 cies, as we have already stated, does not differ from our Branchipus 

 palustris *. The two horns, situated under ihe superior antennae, 

 are composed, in both sexes, of two joints, the last of which, how- 

 ever, is large and arcuated in the male, and very short and conical 

 in the female. In the Br aiwhipus stagnalis^, the horns consist of a 

 single joint, and those of the males resemble the mandibles of the 

 Lucanus: cervus, in their form, dentations, and direction. 



Others have no tail ; their body terminates almost directly behind 

 the thorax and last feet. Such is the 



EULIMENE, Lat. 



The body of the Eulimenes is almost linear, and has four nearly 

 (iliform antennae, two of which are smaller than the others, bearing 

 a great resemblance to palpi, and placed on the anterior extremity 

 of the head. Their head is transverse, with two eyes seated on large 



* Cancer pahidosus, Miill. Zool. Dan. XLVIII, 1 — 8; Herbst., XXXV, 3 — 5; 

 Chirocephalus diaphanus 7 Prev., Journ. de Phys. ; Jurin., Monoc, XX — XXII. 

 See Desraar., Consid. LVI, 2 — 5. This last species i« described in the Manuel da 

 Naturaliste of Duchesne, under the name of Marteuu d'euu douce. 



t Branchiopoda stagnalis, Lat., Hist, des Crust, et des Ins., IV, p. 297 ; Cancer 

 stagnalis, L. ; Gammarus stagnalis, Fab. ; Apus pisci/onnis, ScUaeff. ; Gammarus 

 stagnalis, Herbst., XXX, 3 — 10. 



