208 
CRUSTACEA. 
Sysaiata, Risso : ante Melicerta, ejusd. 
tlip second i)air of claws are larger than the first *, and 
Athanas, Leach. 
In which, on the contrary, the first pair is larger than the second f . 
The last subgcnns of this section, that of 
Pasiph^ea, Sat'., 
Although closely approximated to several of the preceding l)y the 
superior antennae which are terminated by two threads, by the form 
of the four anterior feet, terminating in a didactyle forceps, and pre- 
ceded by a joint, Avithout anmdar divisions, and by the shortness of 
the rostrum, differs from them in several respects. A testaceous ap- 
pendage is very evident at the external base of their feet; these latter, 
Avith the exception of the claAVS, Avhich arc larger and nearly equal, 
are very slender and filiform ; the body is greatly elongated, strongly 
compressed, and extremely soft. 
Pa<:.sivado; Alpheus sivaclo, Risso, Crust., Ill, 2 ; Desmar., 
Consid., p. 240, is tAvo inches and a half long, and four lines and 
a lialf in breadth. The body is trans}»arent, of a nacre Avhite 
edged Avith red, the caudal fin marked Avith small dots of the same 
colour. The rostrum is sharp and slightly curved at the point. 
ClaAVS reddish. 
It is very abundant on the shores of Nice, and according to 
Risso spaAvns in June and July. No other species has yet been 
obseiwed. 
Our fifth and last section of the Macroura, that of the Schizopoda, 
appears to connect the Macroura Avith the folloAving order. The 
feet, none of Avhich terminates in a forceps, are A'ery slender, resem- 
ble thongs, are furnished Avith an appendage more or less long, 
arising from their external side near their base, and serving for 
natation only. The ova are situated betAveen them, and not under 
the tail. The ocular pedicles are very short. As in most of the 
iVIacroura the front projects into a point or rostrum. The shell is thin, 
and tlie tail terminates, as usual, in a sort of fin. They are small, 
and inhabit salt Avater. 
Here the eyes are very apparent ; the lateral antennae are accom- 
panied by a scale, and the intermediaries terminated by tAVO threads 
and composed of several small segments, as in the preceding genera. 
Mysis, Lair., 
Antennae and feet exposed ; the shell elongated ; nearly square or 
cylindrical ; the eyes closely approximated, and the feet capillary, as 
if formed of tAvo threads J. 
* Lijsitiafa seficauda, Risso, Crust., II, 1 ; Desmar., Consid., p. 238. 
p Afhanas iiHescens, Leach, Malac. Brit., XLIV ; Desmar., Consid., p. 239, 240 ; 
de Breb., Crust., du Calv., p. 23, 24. 
t Ml/sis I'uhricii, Leach; Encyc. Method., All. d’Hist. Nat., CCCXXXVI, 8, 9; 
Cancer ucuhdus, Otb. ; Fab., Grand., fig. 1. See Desmar., Consid., p. 241, 242. 
