78 
1885. Hyallnella vesicularis, Jullien, Bull. Soc. zool. France X, p. 
133, figs. 165-172. 
1857. Plumatella punctata, Kraepelin, op. cit. p. 126, pl. iv, figs. 
115, 116; pl. V, figs. 124, 125; pl. vii, figs. 153, 154. 
1890. Plumatella vesicularis, Braem, op. cit. p. 8, pl. i, fig. 8. 
1911. Plumatella punctata, Annandale, op. cit., p. 227, figs. 42 G. 
G 1 (p. 213), pl. iv, fig. 5. 
This species, in а fresh condition or preserved in formalin, is easy 
to recognize on account of the thick gelatinous investment of its zooecia. 
On this account Jullien (1885) proposed to regard it as the type of а 
separate genus (Hyalineifa). А similar investment may be detected, howe- 
ver, though never so strongly developed, in other species of Plumatella. 
There is а single specimen of а form intermediate between the two 
seasonal phases named prostrata and densa by Kraepelin, on а small 
stick from the Jeruslan river. 
The species is widely distributed in Europe and North America and 
by no means uncommon in the neighbourhood of Calcutta. I have also 
taken it at Cuttack in Orissa near the east coast of Peninsular India. I do 
not, however, know of any locality between the Volga and Lower Bengal 
from which it has been recorded. 
Plumatella caespitosa, Kraepelin. 
1887. Plumatella polymorpha var. caespitosa, Kraepelin, op. cit., p. 
123, pl. iv, figs. 109, 110; pl. v, fig. 128. 
This form seems to me well worthy of specific rank. The distribution 
of pigment on the zooecia, their short stout shaped form, the marted 
character of the zoaria, the invariable absence of elongate vertical bran- 
ches, the broad statoblasts surrounded by а swim-ring of uniform width, 
afford together constant characters whereby it may be distinguished 
from its allies. From P. diffusa, Leidy, which it resetnbles most closelyin 
the structure of the zooecia and the zoarium, the outline of the statoblasts 
and of their swim-ring separates it clearly. There is, however, consi- 
derable Variation in the tint of the pigmented basal part of the zooecia, 
which always has а somewhat granulär appearance under the microscope; 
it may be golden brown, deep brown or almost black. 
P. caespitosa is represented in the Volga Collection by two speci- 
mens from the Jeruslan river. Both are on the stems of reeds. The basal 
part of their zooecia is blackish, the distal or upper part completely hya¬ 
line and colourless. The free statoblasts are on an average about 0.323 mm. 
long and 0.212 mm. broad; the width of the swim-ring is about 0.084 mm. 
The form was originally described from Germany. I have examined 
specimens (named by Dr. Kraepelin) from Halle in that country and also 
others from Norfolk in England. The Volga is apparently the most easterly 
locality in which it has yet been found; and there is no certain record 
from America. 
