300 Miscellaneous. 
Immediately after its expulsion, it is seized, in a manner which 
forcibly suggests the supposed action of the Fallopian tube on the 
mammalian ovum at the moment of its escape from the Graafian 
follicle, by the sucker-like extremities of certain remarkable bodies, 
to which the author gives the name of claspers, which are developed 
among the blastostyles, and resemble long filiform and very con- 
tractile tentacles. 
It is apparently now that fecundation is effected ; for the plasma 
becomes again resolved into a multitude of roundish masses. 
This phenomenon may be regarded as representing the yelk- 
cleavage of an ordinary ovum. Reasons are assigned for believing 
that it is through the agency of the claspers that fecundation takes 
place ; and the claspers are compared to the hectocotylus of Cepha- 
lopods, and to certain organs by which fecundation is effected 
among the Alge. 
The mulberry-like mass thus formed, surrounded by its struc- 
tureless membrane, which has now acquired considerable thickness 
and forms a firm capsule, continues to be held in the grasp of the 
claspers during certain subsequent stages of its development. An 
endoderm and ectoderm with a true multicellular structure become 
differentiated, a central cavity is formed by excavation, and the 
germ becomes thus converted into a spheroidal non-ciliated Pla- 
nula. This, after acquiring certain external appendages, ultimately 
escapes, by the rupture of the capsule, as a free actinuloid embryo. 
The actinuloid, on its escape from its capsule, is provided not 
only with the long arms already noticed by Cocks and Alder, but 
with short scattered clavate tentacles. The short clavate tentacles 
become the permanent tentacles of the fully developed hydroid ; 
the long arms, on the other hand, are purely embryonic and transi- 
tory. 
The long embryonic arms originate in the spheroidal Planula. 
They are formed by a true inv agination, and at first grow inwards 
into the body-cavity of the Planula. It is only just before the 
escape of the actinuloid from its capsule that they evaginate them- 
selves and become external. 
After enjoying its free existence for one or two days, during 
which it moves about by the aid of its long arms, the embryo 
fixes itself by its proximal end, the long arms gradually disappear, 
the short permanent tentacles increase in number, and the essential 
form of the adult is soon acquired. 
MISCELLANEOUS. 
On Pinaxia. By Enear A. Surru, F.Z.S., Zoological Department, 
British Museum. 
THis genus was formed by Mr. A. Adams (Proc. Zool. Soc. 1853, 
p. 185) for the reception of a little shell said to have been found 
at the Philippine Islands by Mr. Cuming, and described under the 
