456 ON APPENDICULARIA FLABELLUM 



from the outer tunic in a very curious manner, becoming thrown into 

 folds and sacculations ; and I was almost inclined to seek here for 

 Mertens' " Haus," had not his account been so circumstantiall}' 

 different. 



The distance between the walls of the pharynx and the outer 

 tunic appeared to be considerably greater than in previously-observed 

 specimens, on the neural side, so that the blood-sinuses were here 

 very large, becoming still wider near the ganglion, in consequence of 

 the outer tunic being raised at this point into a transversely-convex 

 protuberance, gradually diminishing towards the sides of the body. 

 The pharynx is richly ciliated, and narrows posteriorly, its wall 

 nearly following the contour of the stomach, so that it assumes the 

 shape of a cornucopia, its tapering hinder portion bending up to 

 terminate in the right division of the stomach. With regard to the 

 endost^'le, I have nothing important to add to my previous account, 

 except that I believe it to be here, as in other Ascidians, the optical 

 expression of the thickened bottom of a fold or groove of the 

 branchial sac. The large apertures described by Gegenbaur (c), at 

 once strike the eye, not only from their size, but from the vehement 

 action of the long cilia with which they are provided. I can in no 

 way account for having overlooked them, and I see nothing for it but 

 to accept the fact of the omission as a practical lesson in scientific 

 charity. The phar3'nx passes on each side into a funnel-like pro- 

 longation (d, c), with its apex directed towards one side of the rectum. 

 The dilated base of this prolongation is continuous with the pharynx, 

 its comparatively narrow apex opens externally beside the rectum. In 

 the mid-length of this conical canal is a thickened circular band {d), 

 formed towards the pharynx of a series of celljeform bodies, placed in 

 a single series, end to end, and externally to this of a transversely- 

 banded substance. It is from this latter portion that the cilia take 

 their origin. They are arranged in several tiers, are very long, and 

 have a strong wavy motion. 



That we have here a direct communication between the pharynx 

 and the exterior, and not, as Gegenbaur states, a communication be- 

 tween the pharynx and certain internal canals, was made clear to me, 

 not onl}' by direct observation of the external apertures, but by feed- 

 ing the animals with indigo. In two specimens this experiment 

 succeeded perfectly ; but it was very curious, that while in the one 

 the current set in at the mouth and out at the apertures, in the other 

 the current was in precisely the opposite direction, in at the apertures 

 and out at the mouth. The wide stomach is bent backwards upon 

 itself, so that its two halves or lobes are pretty nearly parallel, leaving. 



