Apodal Fishes of Bengal. 165 



This is particularly the case with certain genera, in which 

 there is no appearance of any fins whatever, beyond a mere 

 duplicature of the skin near the end of the tail. 



7. The head is very variable in its shape throughout this 

 order; in some species it is depressed and triangular; in 

 others conical ; in others, narrow and high behind the eyes ; 

 but in all the muzzle is narrow. The nostrils have two aper- 

 tures on either side ; one generally tubular placed near the 

 extremity of the muzzle, the other generally placed far back, 

 sometimes even behind the eyes. The eyes are always small, 

 and placed laterally. The mouth is generally moderately 

 cleft, but always extending back as far at least as the eyes. 

 The intestinal aperture is variously placed according to the 

 internal structure of these animals. 



8. Internal structure. — Having noticed briefly those parts 

 which are best calculated to afford the means of distin- 

 guishing the genera and species of this order, it remains to 

 point out one or two circumstances of primary importance 

 that have been overlooked in their structure, and which 

 must in future exercise a great influence with regard to their 

 general arrangement. 



First, as to the situation of the heart. In some we find 

 this organ placed as in ordinary fishes near the gills, or at 

 least no farther back than the branchial apertures.* In these 

 the intestinal aperture is placed about the middle, or some- 

 times before the middle of the body. In others, we find the 

 heart placed considerably behind the branchial apertures, 

 leaving a long thorax which carries the abdominal cavity far- 

 ther back as in serpents, and places the intestinal aperture 

 considerably behind the middle of the body, reducing pro- 

 portionally the length of the tail. The East Indian species 



* Le coeur des poissons est situe dans une cavite particuliere, creusee dans 

 Tangle que laissent entre'elles en arriere les deux ouies, ou fentes branchiales, &c. 

 Cuvier Lecons tl'Anat. Comparee t. iv. p. 226. 



