13 



Sub-class CHONDEOPTERYGII. 



Order Plagiostomata. 



Sub-order Selachoidei. 



In the Fauna of British India, Fishes, Vol. I. p. G, five families of Sharks 

 are recorded for the seas of India, namely, Carchariidse, Lamnidx, lihinodontiddg, 

 Notidanidse, Scylliidas. 



A sixth family, Spinacidm, with two genera, has been discovered by the 

 " Investigator " to be also represented. 



Family Spiiiacidce. 



" Two dorsal fins : no anal. Month but slightly arched ; a long deep 

 " straight oblique groove on each side of the mouth. Spiracles present : 

 " gill-openings narrow. Pectoral fins not notched at their origin. No nic- 

 " titating membrane." {Gilnther) . 



Key to the Indian genera of the family Spinacidse. 



Each dorsal fin with a spine : no lateral folds of skin along the belly : — 



1. Upper teeth erect, with a single cusp : lower teeth 



oblique ... ... ... ... ... Centrophorus. 



2. Teeth equal in both jaws, very small, tricuspid ... Centrosctllium. 



Centrophorus, Miiller and Henle. 



Centrophorus, Miiller and Henle, Plagiostomen, p. 88 : Giinther, Catalogue of Fishes, VIII. 419 (et synon.). 



" Two dorsal fins, each with a spine which is sometimes hidden below the 

 " skin : no anal fin. Trunk elongate without lateral folds. Mouth wide, but 

 " slightly arched : a long deep straight oblique groove on each side of the mouth. 

 " Teeth of the lower jaw with the point more or less inclined backwards or out- 

 " wards. Upper teeth erect, triangular or narrow-lanceolate, with a single cusp. 

 " No membrana nictitans. Spiracles wide, behind the eye. Gill-openings narrow." 

 {Gunther). 



1. Centrophorus Jlossi, Alcock. 



Cenfrophorus Rossi, Alcock, Ann. Mag. Nat. Hist. Angust, 1898, p. 143 : Illdstrations of the Zoology of 

 THE Investigator, Fishes, plate XXVI. fig 3. 



Snout spathulate, much produced, its length measured from the most convex 

 part of the upper jaw is one-eighth of the total, or more than 2^ times the inter- 

 narial space, or about three times the major diameter of the eye-ball. The 

 nostrils, though completely ventral, cause a distinct notching of the margin of 

 the snout seen from above. 



