366 Messrs. Hancock & Attliey on RejptiU- and Fish-Remmns 



the same size and character, and are equal m number to those 

 of the mandible. The largest teeth are nearly one-sixth of an 

 inch in length ; they are much wider than they are thick from 

 back to front. 



On making a longitudinal section of the teeth in the direc- 

 tion of the jaw, the structure is found to be very peculiar. 

 The jaw itself is composed of very dense bone on the sm-face, 

 in which the Haversian canals are well defined, and the ra- 

 diating cells are very numerous and minute ; they are elon- 

 gated-fusiform, with the canaliculi (when observable) sufficiently 

 abundant and arranged for the most part at right angles to 

 the long axis of the cells. In the superficial and denser por- 

 tions of the tissue the cells and tubules are the most minute ; 

 in the deeper portions they are larger and less regular in form, 

 and the bone becomes riddled with medullary cavities, until at 

 length it is entirely reduced to a sort of cellular structure. 

 This curious cellular tissue is continued into the teeth, and 

 forms their central mass, there being apparently no distinct 

 pulp-cavity, or, if any, it is confined to the base. This tissue 

 becomes less open as it approaches, and gradually forms a 

 dense layer at, the surface of the teeth, in which layer the 

 Haversian canals are as distinct as they are in the bone of the 

 ramus, and the cells, diminished in size, assume their regular 

 elongated form, and at the extreme margin they disappear. 

 This peripheral layer, which represents the dentinal wall of 

 ordinary teeth, is found to be continuous from tooth to tooth ; 

 it differs, however, in no respect from the dense external sur- 

 face of the ramus. Indeed it is quite evident that the bone 

 of the jaw is continued into and forms the teeth ; they may 

 therefore be looked upon as processes of the jaw. We have 

 failed to detect the least trace of enamel on the surface of the 

 teeth. 



A considerable portion of one of the pectoral spines lies near 

 to the crushed head of this species, in which the jaws are dis- 

 tinctly displayed with the teeth interlocked. The spine has 

 lost its distal extremity; the fragment, however, is flattened 

 towards this end ; at the basal extremity it is thickened, and 

 assumes a triangular form ; a groove extends along the ante- 

 rior margin. Detached spines have also occurred, agreeing 

 exactly with Sir P. Egerton's description of the pectoral spine 

 of this species. 



The scales are minute rhombs, with the upper surface 

 smooth and slightly convex. Some appear to be minutely 

 and iiTCgularly granulated. Perfectly similar scales clothe 

 the heterocercal tail which was procured at Newsham, and 

 which we believe to belong to this fish. It is about three- 



