V. A PRELIMINARY ACCOUNT OF THE DEVELOPMENT OF 

 THE ELASMOBRANCH FiSHES 1 . 



With Plates 3 and 4. 



DURING the spring of the present year I was studying at 

 the Zoological Station, founded by Dr Dohrn at Naples, and 

 entirely through its agency was supplied with several hundred 

 eggs of various species of Dog-fish (Selachii) a far larger 

 number than any naturalist has previously had an opportunity 

 of studying.' The majority of the eggs belonged to an oviparous 

 species of Mustelus, but in addition to these I had a considerable 

 number of eggs of two or three species of Scyllium, and some of 

 the Torpedo. Moreover, since my return to England, Professor 

 Huxley has most liberally given me several embryos of Scy Ilium 

 stellare in a more advanced condition than I ever had at Naples, 

 which have enabled me to fill up some lacunae in my observa- 

 tions. 



On many points my investigations are not yet finished, but I 

 have already made out a number of facts which I venture to 

 believe will add to our knowledge of vertebrate embryology ; 

 and since it is probable that some time will elapse before I am 

 able to give a complete account of my investigations, I have 

 thought it worth while preparing a preliminary paper in which I 

 have briefly, but I hope in an intelligible manner, described some 

 of the more interesting points in the development of the Elas- 

 mobranchii. The first-named species (Mustelus sp.?) was alone 

 used for the early stages, for the later ones I have also employed 

 the other species, whose eggs I have had ; but as far as I have 



1 From the Quarterly Journal of Microscopical Science, Vol. xiv. 1874. 

 Read in Section D, at the Meeting of the British Association at Belfast. 



