75 
Genus PLUMATELLA, Lamarck. 
1857. Allman, Mon. Fresh-Water Polyzoa, pp. 86 and 92. 
1887. Kraepelin Deutsch. Süssw. Bryozoen i, p. 104. 
1911. Annandale, Faun. Brit Ind., Freshwater Sponges, Hydroids 
and Polyzoa, p. 212. 
There is, as I have pointed out in the work cited above, no general 
Consensus of opinion among students of the Phylactolaemata as to the 
number of species that should be recognized in this genus. Dr. Kraepelin 
attempted in 1887 (op. cit.) to solve the many difficulties involved by 
sweeping away the greater number of specific names previously current 
and grouping the majority of the forms that occur in Germany in two 
species, to which he gave new names. He recognized, however, that these 
names applied to species already well known in literature, viz: Plumatella 
repens and Plumatella emarginata. To the former, with its allies, he gave 
the specific name polymorpha; to the latter, also with its allies, the spe¬ 
cific name princeps. He recognized the very distinct species P. punctata, 
Hancock under its old name. 
Several systematists, especially in Germany, have followed Dr. Krae¬ 
pelin in his revolutionary nomenclature; but it has not been by any means 
universally accepted. А comparison of specimens named by him (for which 
I am indebted to his own generosity and to that of Dr. W. Michaelsen) 
with specimens from India and other countries has convinced me that 
there is greater constancy in some of the forms described by him in his 
valuable monograph than he was prepared to admit with only European 
examples before him, and I do not find myself able to accept the new 
names he has proposed for what he styled the „repens- Reihe“ and the 
„emarginata-Reihe“ 
No less than five forms of Plumatella, in my opinion worthyof speci¬ 
fic rank, are represented in the small collection from the River Volga 
submitted to me. They may be distinguished one from the other by the 
following key: — 
I. Zoarium forming а thick spongy mass with the appearance of а 
honeycomb in transverse section. 
(Statoblasts broad, either markedly asymmetrical or with the swim- 
ring of equal diameter all round the periphery)_ P. fungosa. 
II. Zoarium either dendritic or forming а thin flat layer. 
A. Statoblasts more than twice as long as broad. 
(Swim-ring very narrow; of equal diameter all round the periphery) 
_P, casmiana. 
B. Statoblasts much less than twice as long as broad. 
1. Ectocyst soft, swollen, gelatinous, hyaline. 
(Statoblasts somewhat variable, generally resembling those of P. fun¬ 
gosa but smaller)—______ P. punctata. 
2. Ectocyst stiff, never swollen or gelatinous. 
