506 MATNARD M, METCALF, 



The Äscidiinae I have studied differ from the Cioninae described 

 in the degenerate condition of the rapheal duct and its peculiar con- 

 nection with the rapheal nerve. The two sub-families agree in the 

 dextral asymmetry of the intersiphonal organs. 



The Clavelinidae. 

 Of this family I have five representatives belonging to five of the 

 ten genera: Clavelina rissoana M. Edw., Ecteinascidia turhinata Herd., 

 Perophora viridis Veer., Bhopalaea neapolitana Phil., and Diazona 

 violacea Sav. 



Mhopalaea neapolitana Phil. 



Plate 34, Figs. 6 and 7. 



Rhopalaea neapolitana agrees in general with Ciona intestinalis 

 in the condition of the intersiphonal organs. The gland (gl) lies 

 ventral to the ovoid ganglion (gg). The duct is short opening im- 

 mediately into the large ciliated funnel (cf). In the dorsal raphe 

 we find a well developed nerve {r. w), which is a branch of the right 

 posterior siphonal nerve, and a duct (r. d) continuous above at the back of 

 the gland with the main duct of the gland. The proximal end of this 

 rapheal duct does not, as in Ciona, rise to the level of the dorsal 

 surface of the ganglion before descending into the raphe (Fig. 7) but 

 the whole gland and its appendages are ventral to the ganglion. 

 Though not so shown in the small figure (Fig. 7), the rapheal duct 

 has a central lumen throughout its course. 



Large ganglion cells accompany the fibres of the right posterior 

 siphonal nerve, but very few of them follow its rapheal branch into 

 the dorsal raphe. Smaller cells, probably mesodermal, lie in the 

 neighborhood of the rapheal nerve as elsewhere among the tissues of 

 the raphe, but apparently these have no special connection with the 

 nerve. 



Clavelina rissoana M. Edw. 

 Plate 34, Figs. 8, 9 and 10. 

 This species agrees closely with Rhopalaea, the chief differences 

 being the larger size of the ciliated funnel and the greater devel- 

 opment of the gland which pushes out far on each side of the ganglion 

 (Fig. 9). The rapheal nerve and duct have the same character as in 

 the latter species. 



On the dorsal wall of the gland, just in front of the point of 



