THE EURYPTERIDA OF NEW YORK 75 
_ the articulation between the carapace and abdomen and that between 
abdomen and telson, and the spiniform telson. | 
The other marine animals that have been repeatedly referred to as 
indicating the habits of the eurypterids by their similar swimming feet 
are the crabs of the family Portunidae, notably Matuta and Portunus 
(Huxley and Salter), Platyonichus ocellatus (Hall), and 
Portunus (Laurie). Our most common forms with swimming legs are the 
edible or blue crab (Callinectes hastatus) and the lady crab 
(Platyonichus ocellatus). Here the question arises as to 
whether their last pair of limbs which so strongly resemble the swim- 
ming legs of many eurypterids, are better adapted to swimming or to 
digging. A full account of the habits of Callinectes hastatus 
has been given by Mary J. Rathbun,’ and a shorter account of the habits 
of the edible, lady and green (Carcinus moenus) crabs by Paulmier.’ 
We learn from these descriptions that the edible crab usually wanders about 
crawling or hides under stones and logs and in seaweeds, but when pur- 
sued and finding speed ineffective, will rapidly bury itself in the sand to 
"escape observation. As October draws to a close the crab moves into 
deep water and at this season may frequently be seen paddling near the 
surface as he works himself down stream with the tide. Paulmier states 
that ‘‘as may be supposed from the finlike posterior legs, it is a good 
swimmer and may often be found at the surface.” On the other hand, 
he says of the lady crab, which has quite similar swimming legs: “‘ Its 
usual habitat is the sandy beaches, even the most exposed, when at low 
water mark it buries itself all but the eyes and antennae and is on the 
watch for enemies and prey. If disturbed when feeding or if dug out, it 
disappears with great rapidity, burrowing backward into the sand.” 
We thus infer, and have verified this inference by actual observation, 
that they use their last legs with great ease for both digging and swimming, 
but are more given to a crawling and a burrowing than to’a swimming habit. 
1U. S. Nat. Mus. Proc. 1895. 18: 368. 
aN. Y. State Mus. Bul. 91, 1905, p. 142. 
