Notes on the morphology of the Tunicata. 509 



The Cynthiidae. 

 I have studied nine species of Cynthiidae including representatives 

 of each of the three sub-families, the Styelinae, the Cynthiinae and 

 the BoUeniinae. 



The Cynthiinae. 

 Of this sub-family I have studied four forms — Cynthia pajnl- 

 losa L., Cynthia 2)ynformis Rathke, Cynthia echinata L., smd Cynthia 

 carnea Verrill. 



Cynthia papillosa L. i). 



Plate 35, Figs. 14, 15 and 16. 



In Cynthia papillosa, as in all the Cynthiidae studied, the neural 

 gland lies dorsal to the ganglion. The ganglion is very much elongated 

 (Figs. 14 and 15) stretching from the upper end of the dorsal raphe 

 forward to the ciliated funnel. The funnel shows no features of special 

 interest, except that the horns of the horse-shoe are very greatly 

 coiled, the apices of the coils being pulled out ventrally, giving it the 

 form of a double spiral not coiled in one plane (Fig. 14). 



The neural gland is very long and slender and lies close to the 

 ganglion along its whole dorsal surface (Fig. 15). It is in the form 

 of a tube with but slight irregularities and outgrowths. As in all 

 other species, both those in which the gland is ventral and those in 

 which it is dorsal, the epithelium of the gland on the side next to 

 the ganglion is composed of a single layer of cubical cells bounding 

 the lumen of the gland and continuous with the epithelium of the 

 duct (Fig. 16). The other wall of the gland, opposite to the ganglion, 

 is made up of a similar cubical epithelium, but its cells are in active 

 proliferation, giving rise to a mass of cells so numerous in places as 

 to completely fill the lumen of the gland. These cells frequently drop 

 down and lie in masses against the lower epithelium and the careless 

 observer might therefore think that they had arisen from the lower 

 epithelium. Careful examination, however, shows that the inner contour 

 of the cells of the epithelium of the ventral side of the gland is as 

 definite as their outer contour which abuts upon the basement mem- 

 brane, and one finds no evidence of the division or migration of any 

 of these cells. Here, then, as in all other cases, we find that the 

 glandular tissue arises from that wall of the duct which is most 



1) Cf. Metcalf, 1898. 



