64 SPOLIA ZEYLANICA. 
strongly developed gelatinous investment or synoecium, and are 
bound together when fully adult in a gelatinous investing membrane. 
In this way gigantic compound colonies are sometimes formed. In 
a form allied to P. burmanica, namely, the Japanese P. gelatinosa, 
these compound colonies sometimes reach six feet in length, while 
those of P. burmanica, as it grows in the Sur lake in Orissa, are often 
more than two feet long and several inches thick. The statoblast 
of this species is nearly round, and its hooked processes are very 
short, only being visible under a high power of the microscope. 
‘Dr. Willey’s specimens are peculiar, on account of their small size 
and of the relatively poor development of the synecia. The 
compound colonies consist of only two or three zoaria each, and no 
zoarilum measures more than 10 mm. in greatest diameter ; but 
compound colonies from Orissa often contain hundreds of zoaria, 
some of which measure over 20 mm. in diameter. The polyps of 
the Ceylon specimens are correspondingly small, and their zocecia 
(the cases in which the individual polyps reside) are much more 
distinct from one another than they are in Indian examples of the 
species. Probably these differences are due to differences in 
nutrition. 
The only fresh-water polyzoon hitherto recorded from Ceylonis a 
Plumatella from Colombo, identified by Apstein* as P. princeps, 
Krepelin (? P. emarginata, Allman), a cosmopolitan species or 
rather group of species common in India. 
EXPLANATION OF THE PLATE. 
Fig. 1—Gemmule of Spongilla cartert, « 140. 
Fig. 2—Gemmule of S. proliferens, < 140. 
Fig. 3.—Statoblast of Pectinatella burmanica, X 70. 3a.—Part of 
the edge of the same, x 240. 
Fig. 4.—Free statoblast of Plumatella, sp., x 70. 

* Zool, Jahrb. (Systematic Part), p. 233, 1907. 
