270 
H. L. M. PlXKLl;. 
I camiot be sure whence these pig’ment-bearing cor- 
piiscfes arise. They may be derived from the peritoneum, 
which is so greatly liypertropliied in places, e.g. on the 
afferent vessel (Fig. 15, h. p.), where the cells enlarge and 
then appear to be liberated, also probably some of the cells 
covering the capillary coeca develop into such corpuscles 
instead of ordinary vaso-peritoneal tissue. Cellshaving such 
an origin would be in close relation with the blood-corpuscles, 
and hence able to e.xtract excretory substances similarly to the 
chloragogen cells ol OligochaDtes. 
Eisig states that in the Capitellidae (6, p. 758), whose 
nephridia are limited to small regions of the body, certain 
peritoneal cells laden with concretions are liberated into the 
body cavity (p. 762), and that both blood and peritoneum 
play an important part as true excretory oi’gans, and not 
merely as conveyors of excretory products to other organs. 
The subject of the excretory pigment in Phoronis seems 
to require further study. I have never seen any such pig- 
ment in Ph. hippocrepia, which is the onh^ other species 
of Phoronis that I have personally examined, and can find no 
reference to any. Gilchrist (7, p. 154) mentions the presence 
of white pigment-spots irregularly arranged on the tentacles 
of I’horonopsis albo mac u 1 a ta, but he states that these 
consist of finel}' branching chromatophores. 
Generative Tissue. — All the specimens examined for 
reproductive cells contained ova only, and of these oulj’ a few 
on the left side of the animal arising from the walls of 
capillaries close to their origin from the efferent vessel 
(Fig. 4, oi\). It seems probable that this species is pro- 
tandrous, or possibly dioecious. 
Affinities. — In size and mode of gi'owth this Phoronis 
resembles somewhat closely Ph. ijimai, whose external 
characters were briefly described by Oka ( 13 , pp. 147-8), 
and which was separated from other species owing to 
difference in the length or number of tentacles. Ikeda, who 
has studied the structure of Ph. ijimai (9 and 10 ) .and has 
compared specimens of Ph. hijtpocrepia with it, says that 
