1865. ] OF ANIMALS FROM MADAGASCAR. 469 
veloped. Above brown, penicillated with black, with the bases of the 
hairs blackish grey; below white. In its colour and the length of 
the ear, this species is allied to the South-African Fieldmice, as Mus 
colonus, M. natalensis, &c. 
The Reptiles, which Dr. Giinther has named for me, consist of 
two Snakes (Dipsas colubrina and Herpetodryas bernieri), a Cha- 
meleon (Chameleon lateralis, Gray), several fine specimens of a 
Lizard of the genus Gerrhosaurus (G. lineatus, Cocteau = Cicigna 
ornata, Gray), and an example of another Lizard (Liolepisma belli, 
Gray). All these are species already known to the fauna of Mada- 
gascar. 
The Crayfish I have submitted to Mr. Spence Bate, as our lead- 
ing authority on this branch of natural history. Mr. Spence Bate 
pronounces it to be a new species of Astacus, which he proposes to 
call after its discoverer, with the following characters :— 
ASTACUS CALDWELLI, Spence Bate, sp.nov. (Pl. XXVII.) 
The eyes are planted on short peduncles. The first pair of an- 
tenn have the third joint of the peduncle reaching to the extremity 
of the rostrum. Both branches of the flagellum are slender; and 
the primary branch, which is half as long again as the secondary, 
is about half the length of the anterior division of the cephalon. 
The second pair of antennze are about three times the length of the 
first ; and the flagellum is minutely articulate, each articulus being, 
in length, less than half its breadth, and at the basal extremity being 
about half the breadth of the last joint of the peduncle. The squa- 
migerous process of the third joint is rounded and thickened upon the 
outside, straight, thin, and ciliated upon the inner, and obtuse at 
the apex. The rostrum reaches to the extremity of the penultimate 
joint of the peduncle of the external antennze, rounded at the ex- 
tremity, dorsally concave, the margins fringed within and above 
the actual edge with a rim of short, blunt denticles. The ocular 
orbit is deeply excavate, and armed posteriorly near the centre by a 
small denticle, and at the infero-lateral extremity by a short, sharp, 
curved, and anteriorly directed strong tooth. ‘The lateral walls of 
the cephalon are thickly covered with numerous, subequally distant, 
short, spinous protuberances, which gradually lessen in importance 
towards the dorsal surface of the carapace, which is perfectly smooth, 
except for the well-defined fissure that distinguishes the anterior 
portion of the carapace from the posterior—the demarcation between 
the antennal and mandibular somites. The first or large chelate 
pair of pereiopoda are subequal in size, but differ in form from those 
of every other species of the genus with which I am acquainted, and 
resemble more in general aspect those of the genus Homarus. The 
dactylos is curved inwards, and tipped with a sharp unguis ; the 
dactyloid process of the propodos is similarly formed, and meets the 
dactylos only at or near the apex; the approximating edges, how- 
ever, are armed with a few small and one large tubercle opposite to 
