DECAPODA. 
195 
fectly didactyle hand. The pectoral space inclnded between the feet 
is triangular; the thorax is almost square or sub-cylindrical, and with- 
out any frontal prolongation or rostrum. 
ScYLLARUs, Fah. 
The Scyllari, or Sea-Grasshoppers as they are called, present a very 
us>ial character in tlie form of their lateral antennpe ; the stem is 
wanting and tlie joints of the peduncle, very much dilated trans- 
versely, form a large, flattened, horizontal crest more or less den- 
dated. 
The external branch of the sub-caudal appendages is terminated 
by a leaflet; but the internal one, in some of the males, is a mere 
tooth. 
Doctor Leach has established three genera of them, founded on 
the jDroportions and form of the thorax, the position of the eyes, and 
some other parts. I'hey are, 
1. ScYLLARUS, where the thorax is as long as it is broad or longer, 
and without any laternal incisure, the eyes always situated near its 
anterior angles ; the penultimate joint of the two posterior feet uni- 
dentated in the females. They excavate holes in the clayey soil near 
the shore, which sei’ve them for habitations. 
In one of them the Scyllare ours ; Cancer arctus, L. ; Cigale 
de mer. Rondel., liv. XIII, chap, VI; Herhst,, XXX, 6, the external 
or lateral antennae are much dentatcd. The thorax is marked with 
three longitudinal and dentated ridges, and the superior surface 
of the tail sculptured, but its lateral margin not crenulated. 
The other, Scyllarus cequinoxialis, Fah.; Scyllarus orientals, 
Risso; Squille large, or the Orchetta, Rondel.; Gesn., Hist, des 
Anim., Ill, p. 1097, is large, shagreened, and without ridges. 
Tlie crests are edentated, and the margin of the segments of the 
tail crenulated. Its flesh is highly esteemed, and the ova are of 
a vivid red. 
2. Thenus, whore the fore jiart of the thorax is broader than it is 
long, each lateral margin deeply incised, and the eyes are placed at 
its anterior angles*. 
3. IbacUs, only differing from Thenus in the position of the eyes, 
which are approximated to the origin of the intermediate antennae. 
In an Australian species, Ihacm Pronii, Leach, Zool. Misceh, 
CXIX; Desmar., Consid., XXX, 12, the exterior lateral margin 
of the tliird joint of the external foot-jaws is transversely striated, 
and notched in the manner of a crest j'. In the 
* Themis vuUcus, Leach; Sci/llarus orientalis, Fah.; Humph., Mus., II, D.; 
Herhst., XXX, 1 ; Encyc., Atl. d’Hist. Nat., CCCXIV ; Desmar., Consid., 
XXXI, 1. 
Add Scyllarus antarcticus ; Pahr., Herhst., x.xx, 2 ; Rumph,, Mus., II, D. See 
the article Scyllare, Encyc, M^thodique. 
o2 
