186 Mi: cellaneous. 
Spec’mens sent to me as from the brook were identical with the tank 
species; and therefore, not seeing any reason to question the correct- 
ness of the information received, I did not hesitate, m accordance 
with Mr. Choules’s wishes, to publish the species. It is with much 
regret that I have now to state that it would seem I have been mis- 
informed by Mr. Choules, and that the species does no¢ occur in the 
brook in Bushy Park. Physa acuta must therefore be presumed to 
have been introduced into Kew Gardens from an exotic source. 
Believe me to be, Gentlemen, 
Your obedient Servant, 
Sedgefield, Dec. 30, 1861. ALYRED MERLE NORMAN. 
On the Reproduction of Porpita. By M. Lacaze Duruiers. 
At the end of August and about the middle of September, strong 
gales from the north-west threw upon one of the beaches near La 
Calle some Porpite in good condition ; some of them, preserved in 
my aquaria, displayed their fringed tentacula, moved from place to 
place, and soon let fall to the bottom of the vessel a great number 
of small ovoid bodies marked with a white cross. 
Having seen the small Medusze of the Velelle, I soon, by the aid 
of the lens, ascertained that I had before me exactly similar objects : 
under the microscope no doubt was possible. 
The Medusee of Porpita present the form of a little bell, of which 
the margin is furnished with a delicate membrane, and the summit 
bears a mass of brownish matter formed of large globules or cells. 
Starting from the bottom of the bell, four bands of a very dead 
white run almost to the margin of the orifice; the rest of the sur- 
face is as transparent as crystal. In the thickness of the tissues are 
lodged some small white bacilli, which give their colour to the bands; 
and outside these are scattered wide apart some large neurato-cysts, 
which raise the surface, and almost project from it. 
The movements of contraction are exactly similar to those per- 
formed by all the Acalephs of this form; they are brisk and inter- 
mittent. When the contraction is effected, the water which fills the 
bell is driven out, and pushes before it the little membrane which 
borders the orifice. 
These little Medusee are easily recognized, with a lens, from their 
movements: the arms of the little white cross formed by the bands 
separate from and approach each other in the dilatations and con- 
tractions. 
I could not get these young Porpite to live more than ten days ; 
and all the changes which I could observe in them were limited to 
the almost complete disappearance of the large brown granulations 
at the summit of the bell, the increase of some yellowish granular, 
cells which are observed on each side of the white bands forming the 
cross, the disappearance of some neurato-cysts, and, lastly, the 
formation at the summit of the bell of a cellular nipple, the further 
transformations of which could not be traced. 
The little bodies just described detach themselves from the very 
numerous tentacles which surround the central trunk and clothe all 
