45 8 ON APPENDICULARIA FLABELLUM 



anteriorly, appeared sometimes to present an internal clear cavity, and 

 might then be easily mistaken for ova. But the absence of any 

 germinal spot, the uniformity in appearance of their bodies, in all 

 individuals hitherto examined, and their position, are very great 

 objections in the way of any such view of the matter. 



I must confess that the evidence adduced by Gegenbaur appears 

 to me insufficient to prove that the bodies which he describes in other 

 AppendiailaricB as ovaria are such organs, and for the present I think 

 it is safest to conclude that the female organs of Appendiadaria are 

 unknown. 



With regard to the nervous system and the organs of sense, the 

 only additional observations of importance refer in the first place to 

 the caudal nerve, upon which I found at regular intervals small 

 ganglion-like enlargements (PI. X. [XXVIII.], fig. 4), from which, as 

 well as in their intervals, minute filaments were given off to the 

 adjacent parts. The largest of these ganglia is the lowest, and when 

 the appendage and the body are parallel, it is about opposite the end 

 of the rectum. The nerve here receives a coat of minute rounded 

 corpuscles, so that an oval mass, about i -300th of an inch long, is 

 formed, from whence numerous minute fibrils radiate. The other 

 ganglia contain not more than two to five such corpuscles. 



Gegenbaur states that xl Appendiadaria ftircata be examined from 

 the dorsal surface, an S-shaped cleft, ciliated at its edges, will be ob- 

 served to the right of the ganglion. The cleft, which occurs only in 

 this species, pierces the wall of the branchial cavity, and puts it in 

 communication with the sinus system. 



Seeking for this " cleft " in my Appendicularia {^flabelliim — 

 coplwcerca P), I came upon a slightly different, but I have no doubt, 

 corresponding organ. This is a pyriform sac (q), about i -Sooth of an 

 inch in length, presenting at its wider end an aperture with a produced 

 lip, communicating with the branchial cavity, and by its narrower 

 extremity abutting upon the ganglion. The sac was richly ciliated 

 within, and I have no doubt whatever that it is the homologue of that 

 " ciliated sac," whose existence under different forms appears to be 

 universal among the Ascidians. There is every reason, however, to 

 regard this as an organ of sense, and it never communicates with the 

 sinus-system, so that probably Gegenbaur's statement may be regarded 

 as an error of interpretation. 



I could discover no tran.sverse muscles in the caudal appendage, 

 but only an upper and a lower layer of longitudinal fibres, between 

 which the axis of the tail was enclosed. Whether this central axis is 

 a solid body, or a membranous capsule filled with fluid, I cannot say, 



