BARNACLES 227 



hurting it. The body is enclosed in a broad carapace, 

 shaped much like a heraldic shield, but very convex on 

 the back, and terminating behind in a slender point or 

 spine, which is cut into minute teeth along the edges. 

 Below this shield is seen the body, with three pairs of 

 legs, a great proboscis in the middle pointing downward 

 and backward, and the anal fork, which consists of a 

 bulbous base and two diverging points, which project be- 

 hind under the spine of the shield. 



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 crawling 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 those 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 im- 

 perfect joints, and the second and third pairs are double 

 from the basal joint outward, while the first pair are sim- 

 ple. In the fore part of the body a large eye is placed, 

 deep-seated, which is of a roundish form, and is intensely 

 black, both by reflected and transmitted light. On the 

 summit of the forehead are placed a pair of thick flexible 

 horn-like organs, which are abruptly bent in the middle, 

 and which I believe represent the first pair of antennae. 

 This then is the first stage of the Barnacle the form under 

 which it appears when it is hatched from the egg. 



Among the multitudes which have been evolved during 

 these last few days, and which are now swimming at large 

 in the tank, we may be able to detect some that have 

 passed through their first stage, and having moulted their 

 kin have attained a more advanced form. Here is one, 



