100 ZOOPHYTES. 



it is a single living animal, sustained through the medium of a multitude 

 of subordinate, independent, living animals, forming an integral portion of 

 itself. 



The preceding observations lead to the following conclusions : — 



I. The Cristatella vagans consists of from 200 to 350 individual hydrse, 

 rising as a border from a fleshy mass, which serves as their common 

 basis 



II. The hydra is of ascidian nature, consisting of a body incorporated 

 below with the basis, and terminated above by a head of lunate or horse- 

 shoe form, environed by 100 tentacula. 



III. Each of the hydrse is endowed with separate, distinct, and inde- 

 pendent action, and discharges functions peculiar to itself. 



IV. A locomotive faculty, confined to the fleshy basis only, belongs 

 to the Cristatella, which is exercised although the hydras be in retreat or 

 decay. 



V. Numerous internal ova are generated, and attain maturity in the 

 basis, from whence, in the later season, they are liberated by its decay or 

 decomposition, to float at the surface of the water. 



VI. The contents of the ovum, originally fluid, require 200, 230 days, 

 or longer, for consolidation and maturity of the embryo. 



VII. The foetus developes as a single hydra, with an ample basis, on 

 quitting the ovum. It is subsequently joined by the successive evolution 

 of others, whose ultimate numbers are proportioned to the survivance of 

 the specimen. 



It appears from the history of this animal, that it is suitably charac- 

 terised by the name Cristatella vagans, said to have been given by Lamarck. 

 The genus, believed to comprise only a single species, was instituted by 

 Cuvier. 



Plate XXVII. Fig. 1. Cristatella vagans (Mucedo miralilis), from the garden 



pond at Binns House. 

 2. Another specimen, entire. When bisected, the two halves 

 first receded from each other, and afterwards ap- 

 proached reciprocally. 



