BRANCHIOPODA. 
257 
facility on their back, and their feet, which tliey cannot use for 
walking', while thus employed, present a graceful and undidating 
motion. This motion creates a current between them, which, 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 Withdrawn from its element, it moves its tail for 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 
round her, seizes her by the neck Avith the tAvo horn-like appendages 
of his head, and remains fixed there, until she turns up the posterior 
extremity of her tale, in order to approximate the tAA'o A’^alves of the 
cojjulating organs ; this jjrocess is analogous to the coitus of the Li- 
bellulae. The oA'a are yellowish, spherical at first, and aftei'Avards 
angular; the shell is thick and hard, a circumstance Avhich tends to 
preserAm them. It appears that eA^en desiccation, proAuded it be not 
can-ied 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 freqAiently remarked Branchipi in the little holloAvs filled Avith 
rain Avater, on the summit of the rocks at FontainebleaAi. The female 
Chirocephalus produces several distinct sets of eggs, after each copu- 
lation, at different times, occupying some hours, and even the Avhole 
day in the process. Each set consists of from one to four hundred 
eggs ; they are I’apidly ejected from the female in jets of ten or a 
dozen, and Avith sufficient force to sink them slightly in the mud. 
Benedict PrcAmst has remarked that the Ckir. diaphamis Avas sub- 
ject to certain diseases, of Avhich he gives a description. This spe- 
cies, as Ave have already stated, does not differ from our Branchipiis 
palustris *. The tAVO horns, situated under the superior antennae, 
are composed, in both sexes, of tAvo joints, the last of Avhich, hoAv- 
ever, is large and arcuated in the male, and A'ery short and conical 
in the female. In the Branckipus stagnalis the horns consist of a 
single joint, and those of the males resemble the mandibles of the 
Lucanus cervas, 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 
filiform antennae, tAvo of Avhich are smaller than the others, bearing 
a great resemblance to palpi, and placed on the anterior extremity 
of the head. Their head is transA^erse, Avith tAvo eyes sealed on large 
* Cancer paludosus, Miill. Zool. Dan. XLVIII, 1 — 8; Herbst., XXXV, a — ; 
Chirocephalus diaphamis^ Prev., Jonrn. de Phys. ; .Turin., Monoc., XX — XXll. 
See Desmar., Consid. LVI, 2 — 5. This last species is described in the Manuel du 
Naturaliste of Duchesne, under the name of Marleau d'eau douce. 
t Branchiopoda stagnalis, Lat., Hist, des Crust, et des Ins., IV, p. 297 ; Cancer 
staynalis, L. ; Gammarus staynalis, Fab. ; Apus pisci/ormis, Scbajff. ; Guinmarus 
stagnalis, Herbst., XXX, 3 — 10. 
VOL. III. 
