94 THE ASTER0LEPI8, 



hinder legs of the reptiles and mammals occur, the ischiatic 

 bones generally exist as flat triangular plates, with their heads 

 either turned inwards and downwards, as in the herring, or 

 outwards and downwards, as in the pike ; whereas, in some 

 of the cartilaginous fishes, such as the rays and sharks, they 

 exist as an undivided cartilaginous band, stretched trans- 

 versely from ventral to ventral. And such, with but an up- 

 ward direction, appears to have been their position in the 

 Aster olepis. They seem to have united at the narrow neck 

 A, over the middle of the lower portion of the abdomen ; 

 and to the notches of the flat expansion B, — notches which 

 exactly resemble those of the immensely developed carpal 

 bones of the ray, — five metatarsal bones were attached, from 

 which the fin expanded. It is interesting to find the num- 

 ber in this ancient representative of the vertebrata restricted 

 to five, — a number greatly exceeded in most of the existing 

 l&shes, but which is the true normal number of the vertebrate 

 sub-kingdom, as shown in all the higher examples, such as 

 man, the quadrumana, and in most of the carnaria. The 

 form of this bone somewhat resembles that of the analogous 

 bone in those fishes, such as the perch and gurnard, cod and 

 haddock, which have their ventrals suspended to the scapu- 

 lar belt j but its position in the Cromarty specimen, and that 

 of the ventrals in the various specimens of the Celacanth fa- 

 mily in which their place is still shown, forbids the suppo- 

 sition that it was so suspended, — a circumstance in keeping 

 with all the existing geological evidence on the subject, which 

 agrees in indicating, that of the low type of fishes that have, 

 monster-like, iheiv feet attached to their necks, the Old Red 

 Sandstone does not afibrd a trace. This inferior type, now 

 by far the most prm^alent in the ichthyic division of the ani- 

 mal kingdom, does not seem to have been introduced until 

 near the close of the Secondary period, long after the fish had 

 been degraded from its primal place in the fore-fi^ont of crea- 



