494 SEITARO GOTO 
numerous on the columnellar side of the last whorl, i. e., the side 
on which the hermit crab would slide along in locomotion. On 
the thinner part of the shell they are always very short and com- 
paratively thick, with a single row of filiform tentacles 20-25 in 
number. The hypostome is very prominent and as long as the 
body when the mouth is closed, but flattened out when the latter 
is wide open (fig. 21). On the thicker part of the shell there are 
gasterozooids of a quite different shape, with a slender funnel- 
shaped body, a prominent hypostome and a circle of about 30 
tentacles (fig. 22). The relative numbers of these two forms of 
gasterozooids appear to vary a great deal according to colonies, 
there being no essential difference between them. 
The blastostyles are found where the gasterozooids are few, 
so that we may broadly speak of blastostyle areas and gastero- 
zooid areas, although the two are not rigidly separate and pass 
into each other without any demarcation. The older blastostyles 
are difficult to recognize owing to the great development of the 
gonophores which they bear, and by which they are more or less 
pushed aside from their natural position. In young blastostyles 
bearing a few young gonophores their form stands out very clearly, 
and it is then seen that they are but little different from the slen- 
der gasterozooids above mentioned, except that they are smaller 
all around and the tentacles are less numerous, there being only 
6-12 on each (fig. 23). The hypostome is relatively very large, 
and the mouth is present in older ones. The gonophores are 
borne about midway between the base and the tentacles, and on 
an older blastostyle there may be as many as twelve or more of 
them. So far as I have observed the gonophores develop essenti- 
ally in the same way as in H. sodalis. There are no canals, 
radial or circular, at any time and although in some gonophores 
the ectoderm is much thickened at the top and contains numerous 
nettle cells, there are no tentacles. 
This species is common in different parts of the Bay of Tokyo 
and in the vicinity of Misaki, although it appears to be less so 
than H. sodalis. 
