114 Dr. R. H. Traquair on the Anatomy of Calamoichthys. 



In the genus Polypterus, on the other hand_, the head is rela- 

 tively larger (with apparently little or no latetal expansion and 

 subsequent contraction towards the neck) ; its gently swelling 

 outlines gradually expand and run backwards into those of the 

 body. Suboperculum present; several small plates below pre- 

 operculum. Body relatively much shorter, generally tapering 

 gradually from behind region of pectoral fins, and becoming 

 more compressed laterally towards its caudal extremity. Caudal 

 extremity longer. Scales generally smooth (?). Fins larger; 

 pectorals, fin-rays osseous; anal apparently alike in size in 

 male and female ; ventrals present. 



The genus Calamoichthys agrees, however, with Polypterus in 

 the general character of its numerous dorsal finlets ; lobate pec- 

 torals, two nasal cirri, a spiracle on each side of the head above, 

 and a large flat branchiostegous ray, or jugular plate, on each 

 side of the mesian line below; and also in the hard, osseous, rhom- 

 boidal-shaped ganoid scales, arranged in rows running obliquely 

 backwards, and in the tapering caudal extremity of the body. 



The new genus belongs, therefore, to the same family as Po- 

 lypterus, and would accordingly fall to be placed next to it in 

 the family of the Polypterini. 



Family Polypterini. 



I. Genus Polypterus. 



II. Genus Calamoichthys. 



1. Species C. calabaricus. 



(The specimens described measured from 8 to nearly 13 inches 

 in length.) 



Hab. Old Calabar River, and the Camaroons, West Africa. 



(A female sent by Mr. G. W. Mylne from the latter locality, 

 and recently received by Dr. Smith, was also exhibited.) 



On dissecting those specimens of Calamoichthys entrusted to 

 the author by Dr. Smith, the greatest similarity was found to 

 exist between their internal organization and that oi Polypterus, 

 the chief differences being dependent on the great elongation of 

 the body of the former fish, while the abdominal cavity extends 

 proportionately still further back towards the caudal extremity 

 than is the case even in the genus last mentioned. 



The vertebrae resemble in construction exactly those of Poly- 

 pterus, but are very much increased in number, amounting, in the 

 specimen which was used for the preparation of the skeleton, to 

 110, the first of which has no body, consisting merely of neura- 

 pophyses, spinous process, and a pair of ribs. These latter form 



