of Cartilaginous Fishes. 91 



Myliobatis has the teeth large in the middle, and small on the sides of the 

 jaws. The nasal valve has a straight edge. The fins of the head united. 

 (5 sp.j 



Aetobatis, Nob. has the same fins of the head, hut the lower jaw projects 

 far beyond the upper one. Only one row of teeth in each jaw, and the na- 

 sal valve deeply cut. (2 spj 



In Rhinoptera the fin of the head has an excision in the middle. The 

 teeth are hexagonal plates, large in the middle of the jaw, diminishing in 

 size as they approach the sides. (3 spj 



In the last family, CEPHALOPTERA, we place two 

 genera : — 



Cephaloptera, Dum. Mouth on the under side of the body ; teeth small 

 and pointed, or like tubercles in both jaws. (4 spj 



Ceratoptera, Nob. the type of which is the Cephaloptera described by Le- 

 sueur. The mouth is at the top of the head ; the teeth, distinct only in the 

 lower jaw, are little scales or leaves. (3 spj 



The number of genera indicated in the preceding Synopsis, 

 amounts to 64 ; of which 36, including 85 species, belong to 

 the family of Sharks, and 28, including 96 species, to the 

 Rays. In a paper which we published some months ago, in 

 the ' Reports of the Academy of Sciences, of Berlin,' (July, 

 1837), we enumerated 30 genera of Sharks, and 24 genera of 

 Skates. The genera which we have subsequently added, we 

 found by visiting the collections of Leyden and London. — 

 They are Hemiscy Ilium, Leptocharias, Loxodon, Triakis, Car- 

 charodon, and Rineodon, in the division of the Sharks ; and 

 Platyrrhina, Trygonorrhina, Temera and Hemitrygon in the 

 division of the Skates. 



We gladly avail ourselves of this opportunity to express 

 our sincere and grateful acknowledgements, to the distin- 

 guished naturalists, through whose liberality we were allowed 

 the free use of the collections under their care ; especially of 

 the Museum at Leyden, and, in London, that of the British 

 Museum : also of the collections of the Zoological Society, 

 the Royal College of Surgeons, the London University Col- 

 lege, and that of the United Service Museum. The obliga- 

 tions which we owe to them, and to many others in London, 

 we shall make it a point to advert more explicitly to, in our 

 forthcoming work. With regard however to the genera esta- 

 blished by Dr. Andrew Smith, and which in part are here for 

 the first time brought before the public, we feel bound to em- 

 brace the earliest opportunity of acknowledging the liberality 

 and generosity, with which this eminent individual has as- 

 sisted us in our enquiries, by allowing us to make an unlimit- 

 ed use of the rich collection of Sharks, which he has recently 

 brought from the Cape of Good Hope. 



Berlin, Dec. 12th, 1837. 



h 3 



