754 



MR. C. TATE REGAN ON 



Family 1 . RhinobatiDjE. 



[June 19, 



Dorsal fins two ; caudal fin present ; pectorals of varying 

 extent ; pelvics not notched. Basalia of the dorsal fin in small 

 number (2 only supporting the radials of the fin) ; radials rather 

 numerous, simple, short or of moderate length, not nearly extending 

 to the free edge of the fin. One or more of the radials of the pec- 

 toral fin often articulated directly to the pectoral arch between 

 mesoptei-ygium and metapterygium. Mixopterygia with 3 or 4 

 proximal axial segments, with the marginal cartilages long and 

 extending to the proximal end of the axial cartilage (in Bhinobatus), 

 with three terminal pieces and a large ventral covering piece, 

 and with the glandular body extending nearly to the distal end of 

 the appendage. Vertebral column with the secondary calcification 

 either homogeneous or lamellar in structure, complete or forming 

 8 rays — a dorsal, a ventral, 2 lateral, and the others between them. 



Text-fig. 123. 



Diagrams illustrating the relations of pectoral arch and vertebral column in the 

 Narcobatoidei (A), Pleurotremata (B), and Batoidei (C). 



V, vertebral column ; c, coraco-scapular cartilage ; s, suprascapula. 



In the Prietinse the produced rostrum is armed on each side 

 with a series of teeth and the pectoral fins do not reach the prse- 

 orbital cartilages. The extinct Sclerorhynchus occurs in the 

 Cretaceous and Pristis dates from the Eocene. In the Rhinobatinse 

 the snout is not armed with teeth and the prseorbital cartilages arti- 

 culate with the propterygia. RhinohaUts of the present day had 

 several representatives in Jurassic and Cretaceous times. The 

 remai'ka,ble Jurassic genus Astrodermus should apparent!}'- be 

 placed here. 



