PROCEEDINGS OF SOCIETIES. Q2E 
The session now terminated, embodying in its series of subjects 
matter amply adapted to call forth the active energies of its various 
members. 
Wm. Henpsy, Hon. Sec. 
A PAPER 
On the EMBRYOGENY of COMATULA ROSACEA (Linck). By Pro- 
fessor WyviLLteE THomson, LL.D., F.R.S.E., M.R.LA., F.G.S,, 
&e. 
(From ‘ Proceed. Roy. Soc.,’ Feb. 5, 1863.) 
Arter briefly abstracting Dr. W. Busch’s description of the early 
stages in the growth of the young of Comatula, the author details 
his own observations, carried on during the last four years, on the 
development and subsequent changes of the larva. After complete 
segmentation of the yolk, a more consistent nucleus appears within 
the mulberry mass still contained within the vitelline membrane. 
The external, more transparent, flocculent portion of the yolk lique- 
fies and is absorbed into this nucleus, which gradually assumes the 
form of the embryo larva, a granular cylinder contracted at either 
end and girded with four transverse bands of cilia. This cylinder 
increases in size till it nearly fills the vitellme sac, gradually 
increasing in transparency, and ultimately consisting of delicately 
vacuolated sarcode, the external surface transparent and studded 
with pyriform oil-cells, the inner portion semifluid and slightly 
granular. 
The vitelline membrane now gives way, and, usually shortly after 
the escape of the larva into the water, the third ciliated band from 
the anterior extremity arches forwards at one point; and in the 
space thus left between it and the fourth band, a large pyriform 
depression indicates the position of the larval mouth. At the same 
time a small, round aperture, merely separated from the posterior 
margin of the mouth by the last ciliated band, becomes connected 
with the mouth by a short, loop-like canal, passing under the band, 
and fulfils the function of an excreting orifice. A tuft of long cilia, 
which have a peculiarly undulatory motion, is developed at the 
posterior extremity of the body. ‘The larva now increases rapidly 
in size, assuming somewhat the form of a kidney bean, the mouth 
answering in position to the Adlum. It swims freely in the water, 
with a swinging, semirotatory motion, by means of its ciliated bands 
and posterior tuft of cilia. 
Shortly after the larva has attained its definite independent form 
ten minute calcareous spicula make their appearance, imbedded 
within the external sarcode-layer of the expanded anterior portion 
of the larva. The ten spicula are arranged in two transverse rings 
of five, the spicula of the anterior row symmetrically superposed on 
those of the posterior, By the extension of caleareous network, 
