Holt and Caldeewood — Report on the Rarer Fishes. 393 



Large examples may be uniformly coloured. Under surface white. The linear 

 spines of the back differ from those of other species known to us in their 

 comparatively small size, and greater abundance. The median row may be said 

 to commence just opposite the posterior margin of the spiracles, as in this region 

 there is noticeable an aggregation of very minute spines, hardly larger than the 

 asperities of the general surface. These minute spines, passing backwards along 

 the middle line, increase gradually in size, but cannot be said to become 

 conspicuous as linear spines until the pectoral region is reached. Throughout 

 the whole length of the median row the spines continue to be crowded together 

 in somewhat the same manner as the spinules of the supra-orbital ridges in 

 many species, and frequently, by overlapping each other, present a zigzag 

 arrangement. 



Although attention was specially directed to this species during the survey, 

 as previously unfamiliar to us, we were never able to obtain specimens of 

 less than 16 inches across the disk. All our material being therefore adult, or 

 nearly so, it is impossible for us to speak of any changes of spinulation which may 

 take place during the younger stages. From the very different character of the 

 adult caudal spinulation in males and females, to which we have already alluded 

 in our introductory remarks (p. 381), it is very evident that some changes do occur. 

 A female, 12 inches across the disk, is depicted by Day [op. cit., PI. clxxii.) 

 This specimen has no lateral caudal spines at all. It would therefore appear that 

 the condition of spinulation exhibited by our specimens is characteristic of adults 

 only, the lateral spines, as in the case of R. batis, being only developed late in 

 life. Such a hypothesis may receive some further support from the embryo 

 figured by Couch {op. cit., p. 109), in which, as in very young R. batis, there is a 

 single median row only. The larger specimen described by the same author had 

 a single lateral row. It measured 24 inches across the disk, and appears to have 

 been a female. Day remarks that the general surface is occasionally quite smooth, 

 which may very probably be the case in young examples. He also says, on the 

 authority of some person not specified, that old examples may have the upper 

 surface of an uniform grey colour. All the survey examples, however, were 

 marked in the manner indicated in the diagnosis. 



Fourteen examples were taken during the survey, viz. one in Blacksod 

 Bay, four in Loughrosmore Bay, and nine in Boylach Bay. The last two bays 

 are contiguous. The depth of water varied from 5 to 19 fathoms. It seems, 

 therefore, that the owl ray is extremely local on the Irish coast, as it is too 

 conspicuous a species to have been overlooked if it had been captured else- 

 where. It seems to be essentially an inshore fish, and, previous to the survey, 

 was not known to inhabit Irish waters. It occurs also on the south coast of 

 England, and on the coast of France. 



TEANS. EOT. Bins., SOC. N.S. VOL, V., PAET IX. 3 L 



