CAMBARUS. 3 
lack the bilobed plaited lamina of the Potamobiin, although the stem may 
be expanded into a wing; the epipodite of the first maxilliped almost 
always carries branchial filaments; the coxopoditic sete terminate in hooks ; 
the telson is not divided by a transverse suture.* 
Six genera of Parastacinze have been described ; viz. Astucoides, by GQué- 
rin; Cheraps and Engeus, by Erichson ; Paranephrops, by White ; Astacopsis 
and Parastucus, by Huxley. Some of these genera are based on too trivial 
characters to be valid. The group will be revised in the second part of this 
memoir. 
CAMBARUS. 
In the genus Cambarus, established by Erichson in 1846, + the cephalo- 
thorax is subcylindrical. The last thoracic somite is devoid of gills, neither 
are there any traces of rudimentary pleurobranchix on the anterior somites ; 
the hindmost podobranchia has no lamina. The branchial formula is as 
follows : — 
Somire. { PoOpOBRANCHULE, ARTHROBRANCHLE. PLEUROBRANCHLE. 
Walters ten <0 (aps): en. Oh) in Se 1) 0 = 0 (ep.) 
VIL. 1 1 0 0 = 2 
VIII. Deas 1 1 0 = 3 
IX. il 1 ] 0 3 
X. 1 1 1 0 = 3 
XI. 1 1 1 0 = 3 
XII. 1 ] il 0) — 3 
XIII. 0) 0 0 0) = 0 
6+ep.+ 6 + 5 + 0 = 17+ ep. 
This gives a total of thirty-four branchia, counting those on both sides of 
the thorax. The orifice of the green gland is situate near the apex of the 
* Chilton (Trans. New Zealand Inst., Vol. XV. pp. 152, 163, Pl. xx. fig. 7, 1882) has observed that 
the internal male reproductive organs in Paranephrops setosus axe very different from those in the Potamo- 
biine. In the former the testes are two long tubes united by a transverse commissure, while in the latter 
they form a trilobed organ through the coalescence of the right and left testes posterior to the vasa deferentia. 
I have dissected an undescribed Pavastacine from Chili, and find the testes to agree with those of Para- 
nephrops. It will probably be found that all the Parastacine agree in this regard. On account of the resem- 
blance of the internal male generative organs in Paranephrops and Palinurus, and the further agreement of 
the Parastacine and Palinuvide in the absence of the first pair of abdominal appendages and presence of 
hooked sets, Chilton has forced these groups into too close relationship. Cf. T. Jeffery Parker, in the same 
journal, Vol. XVI. p. 305. 
+ Uebersicht der Arten der Gattung Astacus. Arch. f. Naturgesch., XII. Jahrg., Bd. I. p. $8. 
£ The somite that bears the first pair of maxillipeds is herve reckoned as the sixth. 
