146 



METCALF. 



dorsal tubercle of A. atra is well developed, being of large size 

 and presenting the usual horseshoe-shaped appearance. In A. 

 Marioni and Ph. mammillata, the only other species having 

 accessory funnels, the dorsal tubercle is much reduced. In 

 Phaltusia it may even be wholly absent, or at least so small as 

 to be indistinguishable from the accessory funnels. I have not 

 studied A. Marioni, but according to Roule's description the 

 tubercle in this species can always be distinguished by its size, 

 though not by its shape, from the round accessory funnels. 



A. atra is unique in the following points: (i) in the great size 

 of its neural gland; (2) in the possession of three accessory 

 glands along the duct of the neural gland; (3) in the association 

 in the same individual of a well-developed dorsal tubercle with 

 numerous accessory funnels. This species agrees with A. 

 Marioni and Ph. manimillata in the possession of numerous 

 lateral branches of the neural duct, each opening by one or 

 more ciliated funnels into the peribranchial chamber. 



The discovery of the character of the neural gland and its 

 openings in A. Marioni and A. atra I believe argues strongly 

 against the isolation of Ph. mammillata. The agreement 

 between these three species in so remarkable a character indi- 

 cates, I believe, that the three are more nearly related to each 

 other than either is to the other Ascidiae. If, then, classifica- 

 tion is to express relationship, we should either return Phallusia 

 to the genus Ascidia, or separate A. atra and A. Marioni from 

 the other Ascidiae ; including them under the genus Phallusia. 



FROM THE BIOLOGICAL LABORATORY OF 



THE WOMAN'S COLLEGE OF BALTIMORE, 



May 31, 1897. 



REFERENCE LETTERS 



cf ciliated funnel. 



cf = accessory ciliated funnel. 



d= duct of neural gland. 



d' = branch of duct of neural gland. 



dl= dorsal lamina. 



gg= ganglion. 



/= neural gland. 



gt , gl" , gt" = accessory glands. 



; = longitudinal muscle of intersiphonal region. 



= nerve. 



