﻿PKOCEKDINGS OF THE [July, 1856. 



spine, about one fourth of an inch in length. The whole was covered with 

 the skin and small tubercles or scales ; no part of the bone or the spine, 

 being exposed. 



On the posterior end of the knob, outside of the skin, is a smooth groove 

 or depression, about one inch long and from a quarter to three eighths in 

 width, at the base terminations above in an obtuse point; another three in- 

 ches in length, extends along the dorsal surface of the tail the anterior or 

 widest part being within an inch of the knob. These, we think are nothing 

 more than a modification of the "great plan" upon which all of that family of 

 fish, the Rays, — are constructed. 



The bone — the only bone in the fish — is therefore a modified sting or spine ; 

 and the teeth, like the spine, instead of being very large aud in proportion to 

 the size of the animal, is reduced or modified in like manner to a simple band 

 of semi-cartilage, containing from twelve to fifteen rows of slender enamell- 

 ed processes or asperities, which are true teeth. 



The following table exhibits the dimensions of the several specimens 

 which have been described : 



From the fore-margin of the head 



to the root of the tail, 

 Length of tail, - 

 Across the pectorals, 

 Number of rows of teeth, 

 Spines or stings on tail, - 



Mitchell's. 



Lesueur's. 



Charleston. 

 College 

 Museum 



Mount 

 Pleasant. 



ft. in. 



ft. in. 



ft. in. 



ft. in. 



10 9 

 4 

 18 



numerous 

 none 



7 10 



8 3 

 16 



8 



1 or 2 



7 1 

 5 2 



14 4 



12 



none 



6 2 

 4 2 



14 



14 



none 



Colour. 



C3 H-J 



o > 



.5 £ 

 o ° 



Ph 03 

 cf O 



a 



> a> 

 <Jcq 



2 .5 

 _ _a bo 



5 a> a oo 



^ S " 

 o o 



.2 m 



■S riJ - s 



,p ^5 CO -7-1 

 CD O f-J 



a> o 



<VT3 - 



03 



'I if 



i-si 



© f3 08 



i n3 S3 



.P a 

 -O « 



o> P 

 s o« 

 O) o3 

 rQ On 

 O 



1- 



S 02 

 'S 3 



03 n^j 

 05 



s 



The characteristics of Dumeril's genus " Cephaloptera," are — " Tail slen- 

 der ; the spine, small dorsal, and pectorals broad as in Myliobatis ; but the 

 teeth are still more tenuous than those of a Trygon, and finely serrated. 

 The anterior part of the head is truncated, and the pectorals instead of clasp- 



