History of a transient nervous apparatus in certain Ichthyopsida. 331 



Bd. 2 of Merkel and Bonnet's "Ergebnisse der Anatomie und Ent- 

 wicklungsgeschichte" (p. 450). I have briefly commented upon 

 VON Kupffer's conclusions, which differ widely from my own, in 

 another section. All his results are confirmatory of previous ones of 

 my own. 



Observations on B,aja batis. 



This part of the work is devoted to the consideration of what 

 is to be made out regarding the apparatus in the embryology of one 

 species of Baja. 



Embryos in number of B. hatis, R. clavata and B. radiata have 

 been available, and into all these species investigations have been 

 made. But it was found that of the three species obtainable the 

 embryos of B. hatis ^) showed the apparatus in a more perfect fashion 

 than those of the other two, although the conditions are quite similar 

 in all. B. hatis is, moreover, the species of the three, which, from 

 my own experience, can be most confidently recommended as afford- 

 ing good material for research. On our British coasts it is at least 

 as easily obtainable as the other two forms. The eggs of B. hatis 

 are very hardy and, when taken out of the oviducts, develop readily 

 with a less percentage of mortality than those of B. radiata and 

 B. clavata. From time to time the shark-like "egg-purses" of 

 B. circularis were obtained, but it was never found possible to keep 

 them alive until the embryo was formed. 



But for the generous help of others my material would have 

 been but scanty. To two friends in particular, to the^ late Mr. John 

 Murray, of the Scottish Fishery Service, and to Mr. P. Jamieson, 

 late of the Scientific Staff of the Scottish Fishery Board, I am under 

 deep obligations for all the care, trouble, and self-sacrifice, which 

 they took upon themselves in order to make our skate-culture a suc- 

 cess "'). To them my gratitude may be here expressed, and also to 

 Mr. George Sim, A. L. S., Aberdeen, who kindly procured most of 

 the eggs of B. radiata from which embryos are in my possession. 



1) Only of this species was a complete series of stages obtained. 



2) The wealth of material gained may be gathered from the fol- 

 lowing. Some 520 embryos are in my collection, of these about 380 

 are of B. hatis. Of this species there are all sorts of stages from the 

 earliest traces of segmentation up to newly hatched embryos of up- 

 wards of 19 centimetres. Upwards of 120 of these embryos have been 

 laid under contribution for the present paper. 



