224 ANNALS OF SCOTTISH NATURAL HISTORY 



less as they advance towards the front. There are some- 

 times four rows of these spines, and they form a triangular 

 patch, the long end of which points posteriorly. And lastly, 

 it will be seen on reference to Plate V. that the dorsal 

 spinulation of each form differs widely from the other. 



In reference to the spinulation of the Rays, Dr. Giinther, 

 in his " Introduction to the Study of Fishes," says : " The 

 males of all are armed with patches of claw-like spines, 

 retractile in grooves of the integument, and serially arranged, 

 occupying a space on the upper side of the pectoral fin 

 near the angle of the disc, and frequently also the sides of 

 the head." These spines are certainly not retractile in the 

 British forms. They are firmly set by broad bases into 

 the skin, and are immovable. 



Taking all things into consideration, there seems to be 

 no doubt but that Raia radula must stand as a distinct 

 species. This opinion I have held from the first, but 

 refrained from expressing it until such time as a series of 

 each in all their stages could be obtained. This has, within 

 the past two years, come to hand, and I have now an un- 

 broken series of each species, and I consider that I am 

 warranted in saying that no further doubt need exist that 

 the idea of circularis being the immature form of radula is 

 erroneous. 



This, however, is only one of the many tangled points 

 in reference to the Rays, but enough has been said to show 

 that much work yet remains to be done regarding this group 

 of fishes before the subject can be placed on a satisfactory 



footing. 



EXPLANATION OF PLATES. 

 PLATE IV. 



Fig. I. R. circularis. Fig. 2. R. radula. Males. 

 Figs. 3-6. A', radula. Figs. 7-9. A', circularis. Females. Fig. 10. R. radiata. 



PLATE V. 

 Dorsal Spinulation, etc., of Male R. circularis. 



1. Large and small spines near eyes. 



2. Large and small spines near tail. 



4. Upper teeth. 



5. Lower teeth. 



3. Large and small spines on wings. 



Dorsal Spinulation, etc., of Male R. radula. 



6. Spines near eyes. 



7. Spines on wings. 



8. Spines on tail. 



9. Small spines on tail. 



10. Upper teeth. 



1 1. Lower teeth. 



