Apodal Fishes of Bengal. 169 



and anal, thus tending once more to the restoration of the 

 caudal fin, which we are thus led to expect as one of the 

 characters of the remaining genera. 



Passing through this family we find the development of 

 the vertical fins gradually diminish on the anterior parts 

 of the body, until we arrive at the Gymnomarcena of Lacep. 

 in which the only fin they possess is confined to the extre- 

 mity of the tail. 



We know how differently the structure of an animal 

 may turn out to be on examination, from what we previous- 

 ly expect to find it before hand. Not having met with 

 any species of Alabes or of Saccopharynx, it is with some 

 doubt therefore, that we refer to them in this place. They 

 are distinguished from all preceding fishes, by having but 

 a single branchial aperture. Hence they appear to form a 

 transition from the Anguilliform to the Ophicardian type: 

 but which of the two tribes they really belong to, can only 

 be determined by their further examination. The single 

 branchial aperture indicates a form, leading either to, or from, 

 the family Synbranchidce from which it is distinguished by the 

 presence of pectoral fins. In the order of affinities, the genus 

 Ophisternon seems to succeed next after the American genus 

 Saccopharynx, particularly if we may judge of the form of 

 the body, and the situation of the eyes close to the end of 

 the muzzle. In this genus the branchiae are fully developed, 

 although provided with only one large external aperture. 

 In the next genus Ophicardia, the pectinations of the 

 branchiae become less marked ; both these genera are without 

 scales. They are followed by Pneumabranchus, in which 

 the gills are supplied with a peculiar sack on either side for 

 the respiration of air. The external aperture leading to the 

 gills in the last three genera, is transverse; in the two last, it 

 diverges internally on either side by a short passage to the 

 branchiae. These genera are followed by Synbranchus, which 

 is composed of species distinguished from them by a longi- 



