of certain Fishes of the Ganges. 



45 



ly, forming a hemispherical cavity, in which the interverte- 

 bral fluid is contained, and is united through the medium of 

 this substance, and also by a small triangular process sent off 

 from each side of the cavity of the medulla spinalis, with the 

 bone contiguous to it. The spinous process is bifurcated, or 

 rather consists of two distinct pieces inclining in different di- 

 rections ; and each transverse one, of a short thick spine, groov- 

 ed on its anterior aspect, with a thin plate of a triangular 

 figure arising from it behind, and occupying the whole side of 

 the body of the bone. The ribs, which are extremely small, 

 are attached to the points of these processes as far as the anus. 

 The cervical and caudal vertebrae are distinguished from the 

 intermediate or dorsal ones : the former by the compressed 

 flattened appearance of their bodies, the latter by possessing 

 spinous processes both above and below. 



Organs of Sense. That of smelling appears to be the most 

 perfect. The nasal cavity of each side is tubular, and has 

 two apertures, an anterior one at the extremity of the snout, 

 and a posterior between the eyes : and consists also of two 

 parts, one running forwards, the other extending backwards 

 from the anterior opening in a duplicature of the membrane 

 connecting the malar and maxillary bones, as far as the point 

 of union between the latter and the coronoid process of the 

 lower jaw. The cavities of both the sides have a free commu- 

 nication with each other at their anterior extremities, and may 

 be filled with vermilion injection from one of the apertures. The 

 eyes are very small, and are covered anteriorly by a transpa- 

 rent skin. The thalami optici lie behind the cerebrum, and 

 send out two long slender optic nerves, which cross each other 

 without any incorporation of substance. 



Organs of Respiration and Circulation. Upon the under 

 surface of the throat there is a semilunar aperture, divid- 

 ed below the integuments in the mesial line of the body 

 into two smaller openings, each of which leads to the gills of 

 the corresponding side. The branchial arches arc connected by 

 a strong tendinous membrane, in which arc three small open- 

 ings of an irregular figure for the passage of the water from 

 the mouth, and are covered below, for about one-third of then 

 lenffth. bv a thick muscle proceeding from the bone correspond- 



