64 THE ZOOLOGIST. 
PROCEEDINGS OF SCIENTIFIC SOCIETIES. 
Linnean Society or Lonpon. 
December 19, 1878.—Prof. Attman, F.R.S., President, in the chair. 
Messrs. F. M. Campbell (Hoddesdon, Herts), J. Laurence Hamilton 
(Gloucester Terrace, Hyde Park), and J. J. MacAndrew (Ivybridge, South 
Devon), were elected Fellows of the Society. 
A short paper consisting of a description of some rare shells by 
Mr. Sylvanus Hanley was read. Melania Limborgi, from British India, 
and Leptomya gravida, of uncertain habitat, were specially referred to as 
being unusual in several respects. 
The President made a verbal communication “On the Relations of 
Rhabdopleura,” expressing the opinion that the very anomalous characters 
of this curious Polyzoal genus admit of being derived from the typical 
conformation of a polyzoon by certain easily understood modifications. One 
of the most puzzling of those characters is the apparent absence of an 
endocyst, which necessarily brings with it the absence of a tentacular sheath. 
He pointed out that the endocyst is really represented by the contractile 
cord, which seems to take the place of the funiculus in the freshwater 
Polyzoa, but with which it has nothing to do. In Rhabdoplewra the 
endocyst has receded from the ectocyst, and in its posterior part by the 
approximation of its walls, and the consequent nearly complete obliteration 
of its cavity has become changed into the contractile cord. Anteriorly it 
spreads over the alimentary canal of the polypide to which it becomes 
closely adherent, and here represents the tentacular sheath. Still more 
posteriorly the endocyst undergoes even greater modification, for the con- 
tractile cord becomes chitinized and converted into the firm rod which runs 
through the stem and branches over all the older parts of the colony, and 
which still presents in its narrow lumen a trace of the original cavity of the 
endocyst. The shield-like appendage which is attached to the lophophore 
is one of the most remarkable features in the genus. G. O. Sars regards 
it as representing the epistome of the Phylactolcematous Polyzoa; but this 
view is entirely opposed by the history of its development. Prof. Allman, 
by tracing its development in connexion with that of the polypide, has 
arrived at the conclusion that it is formed as a primary bud, from the 
modified endocyst, aud that in its turn it gives origin to a bud of the 
second order, which becomes directly developed into the definitive polypide. 
The primary or scutiform bud continues for some time to increase in size 
with the developing polypide, which it considerably exceeds, but is at last 
surpassed by the latter. It never disappears, however, but ultimately 
remains in the condition of a subordinate appendage of the polypide to 
which it had given origin. We have thus in the life-history of Rhabdo- 
pleura an alternation of heteromorphic zooids. The first term, however, in 
