STOLOX FORM.-mON IN SPECIES OF TRYPANOSYLLIS. 417 
and so liave developed there moi’e quickly. Johnson’s draw- 
ing (3, fig. 8) shows clearly the conversion of the earliest 
formed transverse rows into semicircles surrounding the 
area of proliferation. 
In IX (PI. 23, figs. 4, 5) the area of proliferation is again 
situated centrally.. The first-formed stolons are, however, 
older than those of VIII, and many of them have been re- 
moved or have fallen off, giving an appearance of irregu- 
larity. 
The Genital Appendage of the Stock. 
I wish here to emphasise one point in Johnson’s descrip- 
tion which is, I believe, a peculiar characteristic of Try- 
panosyllis gemmipara compared with the other forms with 
related reproduction. It will be worth while to quote at 
length the passage bearing on this point : 
'•'Occupying the most dorsal position among the advanced 
buds is the attenuated and rapidly diminishing caudal ex- 
tremity of the stock. It is much like the buds in general 
aspect, and further resembles them in containing sperm-cells 
which are absent in all portions of the stock in front of the 
proliferating region. It differs from the buds in possessing 
(!) a heavily ciliated continuation of the alimentary canal 
(fig. 7, al. c.) ; (2) an anus; (3) and differs in lacking 
cephalisation. In every respect, except that it contains 
sperm-cells, it resembles a regenerated posterior extremity. 
It possesses twenty-four segments, including the pygidium. 
The proliferating region is, therefore, this number of seg- 
ments in front of the posterior extremity. As fig. 7 show.s, 
the attenuated posterior end has almost as much the appear- 
ance of being an appendage to the budding zone as any of 
the mature buds.” 
In PI. 23, fig. 2, a dorsal view of VIII is given, showing this 
caudal extremity,” or genital appendage of the stock, as I 
propose to call it, turned backwards by the growth of the 
stolons ventral to it. Neither the stolons nor the " tail ” 
