218 ON THE TWO SPECIES OF ASTACUS FOUND IN U. C. 
Astacus affinis of the New York work :— 
Rostrum mucronate subcaniculate two spined, a spine behind each 
eye and a larger geminate one each side of the thorax, hand and thumb 
on the inner side, scabrous, length 3 by 3—River Delaware. 
Astacus afinis of M. Milne Edwards. Rostrum short, nearly aa 
broad as long, triangular and slightly toothed laterally. Carapace a 
little granular on the side of the stomachal region. Interior claws 
strong, carpus with a deep depression above, a large tooth within, and 
some tubercles below, hand rounded below; punctuated and tubercu- 
lated near the upper border. Fingers rather long and strong. pis- 
tome short, widened without contraction or traverse groove, length 3 
or 4 inches, inhabits rivers of North America. 
The Astacus fodiens, is the first macrourous crustacean in which I 
have observed a burrowing habit, nor am I aware that this trait has 
been noticed by others. It is by no means unusual in some of the 
brachyura as in the genera Ocypoda, Cardisoma, &c., individuals of 
which so throng the sandy beaches and littoral marshes of the Antilles, 
but these crabs have strong legs, with the last joints armed with a hard 
sharp point well adapted for running and digging in the yielding sand. 
But not so with the delicate cheliferous legs of the slow-moving craw- 
fish, which seem hardly able to bear its weight, apparently little fitted 
for tunneling its way through mud and clay: nevertheless, such is its 
destiny, for when the summer droughts have licked up the 
water on the surface of the swamps, where on the first arrival of 
spring this little crawfish had sported, it commences to seek by boring 
for the moisture of which it is deprived, and like an experienced well- 
digger, begins its work. The diameter of the hole is about an inch, 
and as it brings up the earth in its excavation t piles up the pellets 
round the circumference, till it forms a chimney the height of three or 
four inches. Should an explorer trace these holes downward, he will 
invariably find them terminating in water. In these burrows the 
animal lives during the whole of the dry season, deepening its hole as 
the receding water renders necessary during the night, as the freshly 
excavated wet earth lying round the entrance early in the morning 
testifies. I have never yet taken this species in streams or the Asta- 
cus Bartonii in swamps. I am unaware at what season of the year the 
intercourse between the sexes takes place, but I have found the eggs 
on the egg bearers in November, where they: are carried during the 
whole winter and are hatched at the end of March or the beginning of 
