422 
F. A. rOTTS, 
(3) A female individual with four stolons only (PI. 23, fig. 10). 
These are attached to a narrow terminal pedicle which is the 
dwindled lepresentative of the terminal segment. Three of 
the stolons ai’e of large size, and it is evident that this indi- 
vidual is in the last stage of reproduction, when proliferation 
has ceased and the major portion of the stolons are detached. 
Dorsal to all is a minute prominence which bears the anus (not 
shown in figure but hidden behind stolons). Even at this late 
stage there is no beginningof regeneration of fresh segments. 
This individual consists of 136 se<>:ments altogether. After 
the ninety-seventh there is a marked diminution in the width of 
the segments, and it is likely that the succeeding segments 
represent growth after an earlier period of repi’oduction. 
Comparison of the Stolons of the two Species. 
The stolons of T. cr o ssla n di differ in one or two characters 
from those of T. gemm ipara. In the first place, in correla- 
tion with the smaller size of the stock, they have fewer 
segments and are shorter than those of the latter species. 
The number of segments is nev^er more than eighteen, and 
the longest stolon measured2’5 mm. In T. gemmiparathe 
number of segments lay between twenty and twenty-eight, 
and the average length was 2’5 mm. 
In the structure of the head, the stolons of T. crosslandi 
show themselves more advanced than those of T. gemmipara. 
Both forms possess two pairs of eyes and a brain, but the 
former also (PI. 23 bis, fig. 20) have a pair of minute lateral 
tentacles. Palps are apparently absent but dorsally in the 
angles between the head and the succeeding segment are a 
single pair of well-developed tentacular cirri of greater length 
than the dorsal cirri of the body segments. This comparatively 
advanced condition of the head (“lete dicere”) is attained 
before the separation, and is common to stolons of different 
sizes. Possibly subsequent development of other head appen- 
dages may take place. 
In T. gemmipara Johnson saj's that ‘Dhe head is merely 
