300 Miscellaneous. 



Iinmodiately after its expulsion, it is seized, in a manner wliich 

 forcibly suggests the supposed action of the I'allopian lube on the 

 niainnialian ovum at the moment of its escape from the Ciiraafian 

 follicle, by the sucker-like extremities of certain remarkable bodies, 

 to which the author gives the name of claspers, v\hich are developed 

 among the blastostyles, and resemble long liliform and very eon- 

 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 yidk- 

 cleavage of an ordinary ovum. Keasons 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 Alga>. 



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- 

 niila. 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 Plamda. 

 They are formed by a true invagination, and at first grow inA\ards 

 into the body-ca^dty 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 enjopng 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 niunber, and the essential 

 form of the adult is soon acquired. 



MISCELLANEOUS. 



On Pinaxia, By Edgae A. Smith, F.Z.S., Zoological Department, 

 British Museum. 



This genus was formed by Mr. A. Adorns (rroc. Zool. Soc. 1853, 

 p. 185) for the reception of a little ^hell said to have been found 

 at the Philippine Islands by Mr. Cuming, and described under the 



