THE NEURAL GLAND IN ASCIDIA ATRA. 



MAYNARD M. METCALF. 



JULIN and Herdman have described in Pliallusia mammillata 

 a very interesting condition of the neural gland. Instead of 

 having a single large anterior opening (the ciliated funnel), the 

 gland in this species has many small lateral openings connected 

 by small branched tubes with the main duct. The ciliated fun- 

 nel is always small, and frequently the duct of the gland does 

 not extend far enough forward to open into it. The many 

 small lateral openings lead into the peribranchial cavity. 



Roule has described a similar condition in Ascidia Marioni. 

 This species has numerous lateral openings from the duct of 

 the gland into the peribranchial chamber, and also has a 

 reduced ciliated funnel, the latter, however, always being con- 

 nected with the duct of the gland. 



I have recently found somewhat similar relations in Ascidia 

 aim, from Jamaica, W. I. I have had for examination only 

 two specimens of this species, but as they agree in the char- 

 acter of the parts to be described, there is no room to doubt 

 they are normal characters. 



Ascidia atra is a large black ascidian, shaped much like A. 

 mentula. Its ganglion and subjacent gland lie far back of the 

 ciliated funnel, as is the case in all the Ascidias. The gland is 

 of enormous size, underlying the whole of the much-elongated 

 ganglion and projecting in front of the latter a distance equal 

 to seven-eighths the length of the ganglion (cf. Fig. i). The 

 gland is also of great width and of still greater depth, pushing 

 down into the dorsal lamina, whose upper part is enlarged to 

 accommodate the glandular tissue (cf. Fig. 2). None of the 

 sixty species of tunicates I have studied show a gland whose 

 size in relation to that of the body is so great. 



The duct of the gland shows several features of special inter- 

 est. The main duct extends from near the posterior end of the 

 gland, over its dorsal surface, and forward to the ciliated funnel, 



