RAYS. 43 



ber of medullary canals were fewer, and the proportion of the calcige- 

 rous tubes greater, they were in every respect miniature resemblances 

 of the teeth of tJie full grown fish, such as are figured of the natural 

 size at PI. 8, figs. 3 and 4. 



15. Squatina. — In the monk-fish, [Squatina Angelus), which, msikes 

 the transition from the sharks to the rays, the teeth are arranged 

 along the jaws in well defined vertical rows ; including six teeth in 

 the anterior and gradually decreasing to three teeth in the posterior 

 rows. The margins of the teeth are smooth; a small tubercle pro- 

 jects from the middle of the outer side of the base ; these characters 

 serve to distinguish them from the lower teeth of the Carcharias, 

 which in other respects they pretty closely resemble. It may be 

 further observed, that there is not that difference in the position of the 

 first and second teeth in each row M'hich is so conspicuous in most 

 sharks ; but here, as in the ray tribe, the change of direction of the 

 apex is very gradual and regular from the innermost to the outermost 

 tooth : this character, and the anterior position of the jaws are illus- 

 trated in PI. 10, fig. 2. 



RAIID.E. 



16. The teeth of the rays are, in general, more numerous than 

 those of the sharks ; they have less mobility, are more closely 

 impacted, and in some cases are laterally united together by fine 

 sutures, so as to form a kind of mosaic pavement on both the upper 

 and lower jaws. The Myliobates or eagle-rays, which present the last 

 mentioned condition, — unique in the vertebrate subkingdom, have 

 large and massive teeth ; but in the rest of the present family of 

 cartilaginous fishes, they are remarkable for their small size, as com- 

 pared with those of the sharks. The teeth in some species of rays, 

 are adapted for crushing, but in others they have the middle or 

 one of the angles of the crown produced into a sharp point. In 

 all genera of the ray tribe, whatever the diversity of size and shape 

 of the teeth, they are placed in several rows and succeed each other 

 uninterruptedly from behind. 



In the common skate, (RaiaBatis), the teeth are smaller, much more 

 numerous and the vertical series are more closely approximated than 

 in the Squatina, which is the most ray-like of the sharks ; their gene- 



