RA YS 



3 6 3 



Kays. 



murderous offensive weapons, by means of which large masses of flesh are 

 hacked off. 



The transition from the monk-fish to the typical rays is accom- 

 plished by means of the beaked rays Rlrinobatis and Rhynchobatis, 

 in which the pectoral tins, although large and expanded, do not form such a com- 

 plete disc as in the true rays, while the body is deeper and narrower, and merges 

 gradually into the larger and thicker tail. The more typical rays, as represented 

 by the well-known European thornback-ray (Rata clavatu), all of which are too 

 well known to require description, are characterised by the wonderful ' mills ' 

 formed by their pavement-like teeth, the structure of which varies in the different 

 genera and families. The more important families include the ordinary rays, 

 Raiidce, the electric rays, Torpedinidce, the sting-rays, or whip-rays, Trygonida, 

 and the eagle-rays, 2Iyliobatidat. Of these the eagle-rays are the largest and 



most formidable, especially those of the genera Dieerobatis and Geratoptera, in 

 which the head-fins are prolonged into a pair of horn-like processes projecting from 

 the sides of the mouth. These giant rays, or devil-fishes, as they are commonly 

 called, are inhabitants of all tropical seas, among them being the West Indian 

 Ceratoptera vampyrus, which may measure twenty feet or more across the disc. 

 These gigantic fishes are much dreaded bjr the pearl-divers of Panama, who are 

 reported to be occasionally enveloped beneath their great sail-like fins and thus 

 devoured. 



All devil-fishes, so far as known, produce only a single offspring at a 

 time; this undergoing its development within the body of the female parent, and 

 attaining a large size at birth. The production of but one young one in this way 

 is a rare condition among fishes, although it also obtains among some of the species 

 of sting-rays (Basybatis). At birth the young of the larger devil-fishes are bigger 

 than full-grown common rays of average size : one taken from the body of an 



