106 



513. The maxillary and mandibular arches of a Skate (Raia Batis), showing the 

 crucial ligaments which connect them together on each side. Hunterian. 



514. The maxillary and mandibular arches of a small Skate (Raia Batis). 



Presented by William Clift, Esq., F.R.S. 



515. The upper and lower jaws of a large Skate (Raia Batis). Hunterian. 



515 a. Part of the dental covering of the jaws of a large Skate (Raia Batis). 



Hunterian. 



516. The dental covering of the jaws of a large Skate (Raia Batis). Hunterian. 



517. The maxillary and mandibular arches with the teeth of a Thornback (Raia 

 clavatd) . Hunterian . 



518. The maxillary and mandibular arches with the teeth of a Thornback (Raia 



clavatd). Hunterian. 



519. The maxillary and mandibular arches with the teeth of a Thornback (Raia 



clavatd). Hunterian. 



520. The mandibular arch and its dental covering, together with that of the maxil- 



lary arch, of a Thornback (Raia clavata). Hunterian. 



521. The dental covering of the maxillary and mandibular arches of a Thornback 



(Raia clavata). Hunterian. 



522. The maxillary and mandibular arches of a species of Ray (Raia acutidens), from 



South Australia. They are more completely ossified than in the common spe- 

 cies (Raia Batis), and the points of the teeth are more produced. 



Presented by Governor Grey. 



523. The maxillary and mandibular arches of a species of Ray (Raia parvidens), from 



South Australia, characterized by the minute size of the teeth. 



Presented by Governor Grey. 



