176 CLASSIFICATION OF THE ANIMAL KINGDOM. 



before, and the long cirrhous arms, which by their action expose the 

 blood to the surrounding medium. With regard to their means of repro- 

 duction the most various opinions are expressed, and no two authors 

 seem to be agreed upon the point. They are no doubt hermaphrodite; 

 and, according to Cuvier, the eggs are collected in a large vascular mass 

 covering the liver, and are ultimately expelled through the perforated 

 tail-like organ before spoken of. Others, in direct opposition to this view, 

 state that the foot-stalk of the animal is the true ovary, while other 

 authors, and they are probably correct, make out both to be right by 

 asserting that after the eggs are produced in the manner stated by 

 Cuvier, they are carried by the tail-like ovipositor into the cellular 

 texture of the pedicle, and there retained for some time, when they are 

 again expelled by some means or other from the pedicle, which, while 

 they remained there was of a bluish colour, and are then found occupying 

 the space on both sides of the animal between the body and the shell. 

 The ova at first are of a blue colour; they then become pink, and finally, 

 when ready to be hatched, turn white. 



The second order of Cirrhopods, the Balani, are not fixed on pedicles, 

 but are sessile; and though they differ from the pedunculated type, in 

 their general internal structure, they are not very dissimilar. One remark- 

 able fact connected with the class we are now considering must not be 

 omitted, which is, that all Cirrhopods undergo a distinct metamorphosis, 

 in this respect therefore resembling the families of the Horaogangliate 

 division. The young of the Balani indeed have been taken for little 

 Crustaceans. In this state they are quite free, and skip through the water 

 like the Monoculi in our ponds; they also possess seven pairs of limbs, a 

 jointed setiferous tail, and large pedunculated eyes. In a short time, however, 

 they become fixed to some rock, shell, or other substance; their arms become 

 gradually ciliated, and their eyes quite disappear. The young of the 

 pedunculated Cirrhopods also resemble Monoculi, and undergo similar trans- 

 formations. 



The second family of this division, the Brachiopoda or Palliobranchiata, 

 are so termed from the long arm-like organs with which they procure their 

 food. These organs are situated on each side of the mouth, and in some 

 species can be protruded to a considerable distance, while in others they 

 are confined within the limits of the bivalve shell. Most of them are 

 attached to submarine bodies by a fleshy pedicle, similar to that of the 

 Cirrhopods, as in Lirigula and Terebratula ; but in the genus Orhicula, 

 instead of being fixed by a pedicle, the animals are attached by the lower 

 valve of the shell. The Brachiopods are enclosed within the valves by a 

 delicate membranous lining called a mantle, which is fringed all round 

 with cilia, forming a singular respiratory apparatus, which will be presently 



