186 HUXLEY, ON APPENDICULARIA FLABELLUM. 



Isles was already recorded,* I hardly hoped to find it at acces- 

 sible distances from the shore. During a few calm days last 

 autumn, however, the water of the Bristol Channel, near 

 Tenby, in Caermarthenshire, swarmed with Appendicularice 

 {in company with annelide and crustacean larv2e, Sagitta, 

 echinoderm larvae, Medusce, and Noctilucoi), very little dif- 

 ferent from the southern species which I had previously 

 described, and I gladly seized the opportunity of repeating 

 my observations. 



The length of the body of different specimens varied very 

 much ; from one-fifth of an inch to a fifth or sixth that size. 

 The caudal appendage was three or four times as long as the 

 body, broad, flattened, and rounded at its extremity. The 

 whole animal was usually colourless, except that the stomach 

 had a brownish hue. In one instance, however, the caudal 

 appendage was stained of a bright crimson colour, from what 

 cause I know not. 



With regard to the internal anatomy of the animal, I have, 

 in the main, to confirm the statements I originally made. 

 The oral aperture appeared to be more distinctly bilabiate 

 than I had observed it to be in the southern species, the 

 upper lip hanging over the aperture, and being, as it were, 

 enclosed by the concave edge of the lower. The test forms 

 a thick coat upon all parts of the body, except the posterior 

 region, over the testis, where it is excessively thin. It often 

 separates from the outer tunic in a very curious manner, be- 

 coming thrown into folds and sacculations ; and I was almost 

 inclined to seek here for Mertens' " Haus," had not his 

 account been so circumstantially different. 



The distance between the walls of the pharynx and the 

 ©uter 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 follow- 

 ing 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 endostyle, I have nothing important to add to my pre- 

 vious 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 de- 



* On the coast of Scotland. See Forbes and Hanley, " British Mol- 

 lusca," vol. iv. p. 247. 



