489 



the ventral side. Investigation showed that this did not occur. The 

 testes are sometimes dorsal and sometimes ventral. To a certain extent 

 neighboring gonads have them reversed, e. g. in one dorsal and in the 

 next ventral. 



The second direction of extension of the testes is away from the 

 ovary, as exemplified by Styela, Pelonaia and Goniöcarpa. Dr. Van 

 Name in his recent account of the simple Ascidians of the New Eng- 

 land coast (P. Bost. Soc. N. Hist., vol. 34, No. 13) has indicated the 

 differences between this group and the previous one in his key to the 

 species of the genus Tethyum [= Sty eia). He has however placed those 

 forms with the testes close beside the ovary in one group with those in 



Fig. V. Parolona elata; 1, a gonad viewed from the side; 2, a testis. Pandocia fi- 

 brosa; 3, a gonad viewed obliquely; 4, a testis. (1, 2 and 4, X 27; 3, X 21.) od, ovi- 

 duct; vd, vas deferens; ve, vas efferens; ov, ovary; te, testis. 



which the ovary overlies the testes and includes in this group the Asci- 

 dia plicata of Lesueur. My study of specimens of this latter species 

 from Naples shows that the testes are as distinctly separate from the 

 ovary as in Sty eia partita. All the species that I have examined show 

 no intergrading between those forms with the testes growing under the 

 ovary (Fig. II) and those with the testes growing away from the ovary 

 (Fig. Ill and IV). In immature individuals of the genera Sty eia, Pelo- 

 naia and Goniocarpa there is a definite interval between the testes and 

 the ovary. Dr. Van Name has figured this for a young Pelonaia. Later 

 the ovaries and testes may enlarge so much that they come together or 

 the testes may even grow over the ovary as occasionally occurs in Go- 

 niocarpa. This is quite secondary. 



