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Part III. — Evjhtli Annual Report 
VI. — ON THE DEVELOPMENT OF THE COMMON SKATE 
{Raja batis). By Dr J. Beard. 
(Plates IX.-XI.) 
Although the skate is one of the commonest elasmobranch fishes of our 
seas, very little has been written of its life-history and development. The 
sharks and torpedoes have mainly yielded material for embryological work 
on elasmobranch fishes. Indeed, to such an extent have these latter 
forms been studied, that it would be easy to make a list of some hundred 
or more memoirs dealing with the development of the various organs of 
Scylliurn, Acanthias or Torpedo. 
Our knowledge of their embryology practically dates from 1874-75, 
which saw the first fruits of the memorable researches of Balfour and 
Semper. Since then, almost every embryologist who has paid attention to 
fish-development has contributed something to our knowledge of elasmo- 
branch fishes. 
Of recent years the rays find little mention in embryological works, 
and beyond a few papers and some observations on particular organs 
by Van Bemmelen, Dohm, Ewart, Van Wyhe and others, our knowledge 
of their actual development has advanced no further than the point at 
which it stood in 1864, after ths appearance of Professor Wyman's 
memoir.* 
As the volume containing this work is rarely f met with in libraries, it 
may be well to give some account of Wyman's results. 
Our author commences with a fairly accurate description of the egg-case 
or 1 purse. ' One or two small points in his account may be corrected 
later on, when I describe those ' purses ' of rays which have come under 
my own observations. It may, however, be remarked that Wyman's 
description does not apply to the purse of the British Raja batis, and 
from several circumstances, to be afterwards detailed, I conclude that 
Wyman was in error in supposing that the purses he examined were those 
of R. batis, and that the form he really investigated was R. oculata 
(Mitchell). The memoir is illustrated by one plate, containing eleven figures. 
These figures relate to but five embryos, and the text also bears evidence 
of the paucity of the material at the author's disposal. The earliest 
embryo depicted showed four well-marked gill-slits. The drawing is not 
very accurate, and from various circumstances (viz., the size of the 
embryo, the great development of the unpaired fins, and the extensive 
yolk-sac circulation) it may safely be concluded that the whole number of 
gill-slits was really present, and, indeed, that the external gill-filaments 
were in course of development. Probably with reference to its great 
length and tenuity Wyman describes this embryo as 1 eel-shaped. ' 
In the second stage figured the embryo was much further advanced. Its 
most characteristic features were the fairly developed gill-filaments, the 
well-marked anterior and posterior paired fins, and an anal-fin. The next 
embryo was well described as 'shark-like;' it showed a second anal fin 
behind the first, and Wyman found that these two fins are temporary 
structures, which disappear in later stages. 
The following embryo had taken on many of the skate characters. It was 
* Wyman Jeffries, 1 Observations on the Development of Raja batis, 7 in Memoirs 
of the American Academy of Arts and Sciences, vol ix., 1877, p. 31-44. (The 
volume is dated 1867, bur contains memoirs extending from 1864 to 1873. 
t My thanks are due to H. Webster, Esq., University Librarian, Edinburgh, and 
to the Royal Society of Edinburgh for opportunities of consulting this work. 
