34 ■ RECORDS OF THE AUSTRALIAIV MUSEUM. 



position of the ventral fin is so striking and so constant that I 

 feel compelled to regard the two as distinct, and Mr. Ogilby since 

 tells me that he now holds the same view. 



In S. megalops the ventral fin occupies a much more forward 

 position, the centre of its fleshy base being exactly midway 

 between the end of the snout and the termination of the upper 

 caudal lobe, while the anterior insertion of this fin is below the 

 middle of the space between the origin of the two dorsals. An 

 examination of any specimen of •S'. acanthias, shows a much more 

 posterior situation of the ventral. 



Very many of the examples which I knew so well on the York- 

 shire coast under the name "Sea-dog," exhibited white spots; in 

 the young they were generally to be traced. These features are 

 recorded by Day, Yarrell, Couch, and other writers on British 

 Fishes. I have not seen a spotted example of S. megalops, and 

 the fcetal specimens above referred to show no trace of such. The 

 point of each dorsal spine in this species is covered by a little 

 knob, a feature referred to in S. acanthias by Mr. Robert Ball as 

 follows : — 



"Mr. Ball brought under notice of the Academy, as an 

 unobserved fact, a beautiful provision in the fcetus of the 

 Spined Dog-fish (Acanthias vulgaris), by which the mother is 

 protected from being lacerated by the spines of the young before 

 birth. He exhibited two perfectly developed young, which he 

 had taken from the mother on the 30th November last; in these 

 the spines were each covered at the point with a small knob of 

 cartilage, fastened by straps of the same material, passing down 

 one on each of the three sides of each spine, in such a manner as 

 evidently to become easily detached at birth, thus allowing the 

 little animal to commence life effectively armed. He mentioned 

 that the female in question contained a large number of eggs, in 

 various states of development, in addition to the two fully-formed 

 young."" 



The drawing of the foetal Shark, reproduced by Richardson," 

 evidently represents Squxlus acanthias, and not S. megalops, as 

 indicated not only by the posterior position of the ventral fin but 

 also by the presence of the white spots. On comparing this figure 

 with my illustration, the difference in the comparative size of the 

 eyes is very striking, much more than in the adults, though it was 

 this peculiarity which induced Macleay to bestow upon his species 

 the name megalops. 



The example figured, of the natural size, measures 162 mm. in 

 length. 



6 Ball— Proc. Koy. Irish Acad., iii., 1847, p. 230. 



7 Richardson— Voy. Ereb. and Terr , Fish, 1S4G, p. 44, pi. xxviii., figs. 1 

 and 2 {error e fig. 5 in text). 



