﻿FIELD AND FOREST. 75 



an active little creature, having more resemblance to a cray-fish or lob- 

 ster than to its parent crab. It crawls with considerable rapidity over 

 the muddy and sandy sea-bed in shallow water; or swims in shoals 

 or streams, of two feet or more in width, with great regularity and 

 precision of movement. Each beside the other swims with steady 

 stroke, near the surface, and leading in one direction, usually towards 

 the deeper water. 



Its body is whitish translucent, glistening, and the shell so thin as 

 to be almost transparent. Its eyes are very bright blue, and being 

 quite large heighten the pleasing effect of its appearence as it move?, 

 through the water. The head is almost quadrangular, raised like a 

 tablet, with the front margin triangular and provided with a long slen- 

 der stylet, projecting forward from the centre. The carapace is strik- 

 ingly different from that of the older crab ; it is long-quadrangular, 

 raised above the level of the abdomen, and the sides are rounded off 

 and slightly sloping towards the under side. Its four pairs of hind 

 legs resemble those of the adult, except in the last joint of the poste- 

 rior pair, which is not widened into a broad paddle, but, while being 

 of the shape of a sword-blade as the others, is a little more expanded, 

 and adapted both for swimming and creeping. Besides this the tip of 

 each foot is provided with a slender spine, which enables the creature 

 to hold firmly to any object upon which it may alight. 



The abdomen stretches back long and narrow, a little tapering to- 

 wards the tip, not having the tail expanded as in the lobster, but with 

 the end piece long-quadrangular, a little rounded behind, and termi- 

 nated by a few slender threads. 



Vast numbers of this Megalops were observed by me on the fourth 

 day of this month in places where the female Callinectes was incu- 

 bating. A few Zoeas were in the swarms, and I was enabled to 

 secure a large supply of specimens. The muddy sand was crowded 

 with them around the female crabs, so that stirring of the bottom 

 set them streaming in every direction. They were observed in many 

 places, both at an earlier and later date, but never in such remarable 

 swarms as on that occasion. The weather had then been calm for sev- 

 eral days, and the remarkably hot season no doubt favored their de- 

 velopement. They generally measured 3 millemetres in length, by 1 

 millemetre in width, while the abdomen was scarcely more than a half 

 millemetre in width. 



