IS RAIA RADULA A GOOD SPECIES ? 223 



Again, these same white markings, similarly arranged, are 

 to be seen as frequently upon Raia radiata, a form which 

 no one would think of confounding with either of the species 

 under consideration. Eighth, the proportion of females 

 over males in radnla is extraordinary. From 7th May 

 1892 until 5th July 1895 I kept a daily record of all the 

 examples of radula that were brought into Aberdeen Market, 

 and within that period 2865 females stood against 123 

 males ; whereas in the case of circularis, from I5th August 

 1894 until i 2th July 1895, the numbers were 2237 females 

 and 2381 males, showing an excess of 1 44 males over females. 



Now, the question arises (and has to be answered by 

 those that hold the two forms to be the same), What becomes 

 of the excess of males in what some writers are pleased to 

 call its immature state ? It may also be asked, Why is 

 there such a paucity of males when the fish is in what they 

 term its adult state ? And further, At what stage of their 

 existence does the change take place, in the form, external 

 colour, and markings of the two forms ? If reference is 

 made to Plate IV. there will be seen a series of Raia radula, 

 ranging from 7^ inches to 30 inches across its broadest 

 part ; and in the case of Raia circularis, from 3 inches to 

 its full size of 18 to 22 inches, broader than which I have 

 never seen it. Besides this, circularis is quite abundant, 

 and breeds freely in Aberdeen Bay and along the coast both 

 north and south, while radula is entirely absent from that 

 ground, and is not to be found until we reach deep water to 

 the north of Wick. Again, if circularis is the young of 

 radula, how is it that not a single example of it is caught 

 in company with radula ? One would naturally expect 

 that the immature stage would occasionally be found with 

 the adult. 



The nature and distribution of the spines of the two 

 forms differ, radula having a few strong irregularly-placed 

 spines upon the nose, and three rows of from seventeen to 

 eighteen spines on each " wing," and the anterior end of 

 these rows does not come nearer the edge of the fin than i^- 

 inches. On the other hand, circularis has no strong spines 

 upon the nose, and those on the " wings " come right up to, 

 and extend along, the anterior edge, the spines becoming 



