No. 376.] .SARCOSTYLES OF THE PLUMULARIDZ. 227 
Curiously enough, one of the earliest observers of nemato- 
phores published in 1863 a figure of a sarcostyle which was 
represented as having a body cavity. The author referred to 
is Semper, and the figure is found in the Zeitschrift fiir wiss. 
Zoologte, Bd. xiii, Pl. XX XVIII, Fig. 4 a. 
The conclusion that sarcostyles are morphological persons of 
the colony is borne out by almost every known fact concerning 
them. Embryological investigation shows that they are formed 
in almost exactly the same manner as the hydranths, and that 
they make their appearance as early as the latter and often 
earlier. It is possible, moreover, to point out a series of forms 
leading from the so-called “ fighting zooids” of Hydractinia to 
the typical nematophores of the Plumularidz. In the genus 
Ophiodes we find organs or persons almost exactly intermediate 
between the Hydractinia and true sarcostyles. Prof. Baldwin 
Spencer has lately described a new family of Hydroida, called 
the Hydroceratenide, evidently closely allied to the Plumularide, 
with numerous fighting persons which are histologically almost 
identical with true nematophores; the extreme extensibility, how- 
ever, of the latter has not as yet been observed in the former. 
There appears also to bea curious cross relation between the 
dactylozooids of the Millipora and the sarcostyles, if such they 
be, of the Hydroceratenide. 
Among the many perplexing questions in this connection is 
the one raised by Professor Allman, who very strongly urges 
the relationship between the nematophores and the denticles 
of the graptolites. His argument would lead to a belief that 
the ancestors of the Plumularide may be the graptolites; that 
the nematophores of the former are the homologues of the 
denticles of the latter; that we have in the sarcostyle the 
original type of the hydranth ; and that the present hydranth is 
really a very highly specialized sarcostyle. 
As before indicated, the sarcostyles often precede the hy- 
dranths in the development of the colony, and would thus 
appear to be an older structure in phylogeny. 
' I was unable to confirm Merejkowsky’s statement that the 
extensible part of the sarcostyle was composed of ectodermal 
cells immersed in free protoplasm. Indeed, it appears that no 
