The True Sharks 



551 



bottoms. The length of the snout differs considerably in 

 different species, but in all the body is relatively long and strong. 

 Most of the species belong to Rhinobatus. The best-known 

 American species are Rhinobatus lentiginosus of Florida and 

 Rhinobatus productus of California. The names guitar-fish, 

 fiddler-fish, etc., refer to the form of the body. Numerous 

 fossil species, allied to the recent forms, occur from the Jurassic. 

 Species much like Rhinobatus occur in the Cretaceous and Eocene. 

 Tamiobatis vetustus, lately described by Dr. Eastman from a 

 skull found in the Devonian of eastern Kentucky, the oldest 

 ray-like fish yet known, is doubtless the type of a distinct 

 family, Tamiobatida. It is more likely a shark however than 

 a ray, although the skull has a flattened ray-like form. 



FIG. 343. Guitar-fish, Rhinobatus lentiginosus Garman. Charleston, S. C. 



Closely related to the Rhinobatidce are the Rhinidce (Rham- 

 phobatidcz), a small family of large rays shaped like the guitar- 

 fishes and found on the coast of Asia. Rhina ancylostoma 

 extends northward to Japan. 



In the extinct family of Astrodermida , allied to the Rhino- 

 batidcz, the tail has two smooth spines and the skin is covered 

 with tubercles. In Belemnobatis sismonda the tubercles are 

 conical; in Astrodermus platypterus they are stellate. 



Rajidae, or Skates. The Rajida, skates, or rays, inhabit the 

 colder waters of the globe and are represented by a large number 

 of living species. In this family the tail is stout, with two- 

 rayed dorsal fins and sometimes a caudal fin. The skin is 

 variously armed with spines, there being always in the male two 

 series of specialized spinous hooks on the outer edge of the 

 pectoral fin. There is no serrated spine or "sting," and in 

 all the species the eggs are laid in leathery cases, which are 



