252 - ZOOPHYTES. 



haps the same may be said of all the more minute hydrse, for they must 

 be very readily affected by transitions of site, or the alteration of tempe- 

 rature. When withdrawn from the water, the largest specimen merely 

 resembles a quantity of wet moss. 



The natural colour is grey, with the faintest tinge of pink. 



It occurs in great profusion, and sometimes many of the hydrae are 

 alive and vigorous. 



Specimens were kept from the end of September until the beginning 

 of January, when the vessel, a tall narrow jar, being emptied of its con- 

 tents, at least 50 minute specks were seen adhering to the sides on re- 

 plenishment. They tended to an elliptical form, and several exhibited 

 small white projections. A very minute hydra, with eight tentacula, after- 

 wards sprung from one of them. 



Plate LI. Figs. 3, 3. Valkeria spinosa. Extremity of a branch, enlarged. 



This is a single extremity, cleft down the middle, to obtain 

 room for it on the Plate. 



NOTE. 



There is commonly much irregularity in the position of single cells, 

 of pairs of cells, or of masses and clusters of them, even in all subjects. 

 Certainly this denotes a great inequality of the vital forces. It might be 

 ex])ected that in genera and in species uniformity should prevail, whereas 

 only analogies are presented, and, for the most part, those but of a remote 

 or general character. 



The jireceding genus, Valkeria, embraces ascidian hydra? with eight 

 ciliated tentacula. Another genus of ascidian hydrse, but with ten ciliated 

 tentacula, is proposed under the name of Bowerhankia or Laqemlla. 



Considerable general resemblance appears between the hydrte and 

 cells of these two. But more minute and accurate examination may prove 

 their difference in other points, though the number of tentacula coincides. 



Two species, if I be not mistaken, both with ten tentacula, inhabit 



