BAKNACLES. 227 



without hesitation, if you kncM" nothing of their pa- 

 rentage, assign them to that well-known genus. Tlieir 

 movements are almost incessant, a series of jerking 

 progressions performed by quick but apparently labo- 

 rious flappings of the limbs, right and left together. 

 They occasionally rest from their exertions for a few 

 moments, but seem to have no power of alighting on 

 any object. 



But in order to obtain a more precise idea of the 

 structure of this tiny creature, we must manage to 

 restrain its liberty a little, by applying gentle pressure 

 with the compressorium, just sufficient to confine it 

 without hurting it. Tlie body is inclosed in a broad 

 carapace, shaped much like a heraldic shield, but very 

 convex on the back, and terminating behind in a slen- 

 der point or spine, which is cut into minute teeth along 

 tlie edges. Below this shield is seen the body, with 

 three pairs of legs, a gTeat proboscis in the middle 

 pointing do>vnwards and backwards, and the anal fork, 

 which consists of a bulbous base and two diverging 

 points, which project behind under the spine of the 

 sliield. 



The legs are exclusively swimming organs ; they 

 have no provision for grasping, no claws or hooks, nor 

 do they appear to be capable of being used for crawl- 

 ing on the ground or for climbing among the sea-weeds. 

 They are fringed along one edge with long and stout, 

 but somewhat flexible spines, of which tliose that are 

 nearest the trunk seem more rigid, and are directed 

 more at right angles to the limb than the rest. The 

 legs are formed of many imperfect joints, and the 

 second and third pairs are double from the basal joint 

 outwards, while the first pair are simple. In the fore 



