64 W. FELL WOODS ON THE RELATION OF 



vesicle, germinal spot, or vitelline granulations, its first step is 

 elongation, it then becomes oval, after which nipples appear, which 

 also elongate, &c. Whereas I have shown eggs to be contained in 

 the tube, and spheres, not perfectly clear, but of the same 

 structure as that which the embryo continues to exhibit until it 

 approaches its full development. 24 These spheres become oblate, 

 and then follow the course described by our author. He omits, 

 however, to state that this development is made, until near the final 

 stage, within an elastic membrane, in which I have seen the 

 embryonic tentacular filaments uncoil and re-coil. 25 The well- 

 developed creature seems to me to display not one but three 

 cavities, 26 or if that in rear of the mouth is really one with the 

 central cavity, I find another near the base, which no doubt also 

 communicates with the latter. Both are so variously distended and 

 contracted that their apparent size and position are very changeful, 

 but when they approach each other most nearly they appear to be 

 separated by a very well-defined partition. A rough outline may 

 serve to indicate this. 27 I am not sure that the basal filaments are 

 attached precisely in the manner shown by the French writer. He 

 also evidently considers them as cylindrical, which they may be : but 

 I once watched one of a pair which had been detached in the tube, 

 and it continued its contortions for a long time, as when well- 

 developed they always do, allowing its base end especially to be very 

 fairly seen through the tube. The filament appeared more like an 

 eel cut open than a cylinder, the edges being curved inwards ; this 

 was caused, I think, by a groove or channel along its centre. 28 It 

 is questionable whether the basal appendages are a necessary 

 feature of every Bucephalus ; whilst many partially developed are 

 only mutilated by accident, 29 there are many very well advanced 

 which appear fairly perfect without them, and I doubt if sufficient 

 detached limbs could be found to match them. Is it possible 

 there can be a difference of sex with which these are connected ? 

 Since, also, I have never seen any Bucephalus which exhibited a 

 contour exactly corresponding to either of the French drawings of 

 Haimeanus, there may be a slight difference in the English kind. 



" June 14, 1872. February 18, 1873. March 12, 1874. Fig. H. 

 25 April 11, 1873. April 29, 1873. May 20, 1873. Figs J 1 to 5. 

 2<s April 29, 1873. May 20, 1873. May 27, 1873. 



«7 June 16, 1874. November 25, 1874. December 9, 1874 (No. 6). Figs. 

 K 1 to 3. 



28 November 25, 1874. Fig. L. 

 20 February 18, 1873. 



