OSSEOUS SYSTEM. 187 



ticulated throughout their whole extent by transverse joints (radii 

 articulati), as is exemplified by the majority of our freshwater Fish, 

 e. g., the Carp, Pike, and Flying-fish or Exocetus. The Osseous 

 Fishes have accordingly been divided into two great groups, the 

 Acanthopterygii or spiny-firmed, and Malacopterygii of soft-finned ; 

 an arrangement, however, which does not admit of perfectly precise 

 definition. The pectoral, ventral, and caudal fins, are always provided 

 with soft articulated rays. 



OSSEOUS SYSTEM. 



IN the external arrangement and structure of its several component 

 pieces, the Skeleton of Fishes exhibits by far the greatest diversities 

 of all the classes of Vertebrated animals. 



As regards the Osseous Fishes, their skeleton indeed offers the 

 greatest analogy to that of the other Vertebrata, but even this, upon 

 a closer examination, is found to be less than it at first sight ap- 

 pears. For upon first commencing its study, we are too apt to 

 carry out the doctrine of analogy to the utmost extent, while, as we 

 advance, a higher and more philosophical method of comparing the 

 structure of the skeleton, namely, that which is based upon the 

 history of its development throughout the several classes of Verte- 

 brata, suggests itself, and causes many apparent analogies to dis- 

 appear. 



The minute organization of the bones in Fish is still but little 

 known. The cartilage and osseous corpuscules are never so distinct 

 as in the other Vertebrata. 



The Cranial bones of the Osseous Fishes, though exhibiting seve- 

 ral remarkable varieties, admit of being contrasted to a considerable 

 extent with those of the higher Vertebrata, and even the human 

 subject. Our best plan will be to select for the purposes of illus- 

 tration the skeleton of a Carp, as one which presents a tolerably 

 normal type of structure, and is generally found ready prepared and 

 mounted in niuseums, or else that of the common Perch and Pike. 



The Occipital bone consists very generally of six pieces, two of 

 which are single, or not in pairs. The body, still very similar in 

 character to that of a vertebra, is not united to the first cervical by 

 means of a joint, but immoveably by means of firm ligaments, like 

 the other vertebrae. In the Carp the body of the occipital bone is 

 actually provided, inferiorly, with a strong pointed process project- 

 ing backward, and which supports a broad plate invested by car- 



