37 



unfortunate infusorians or monads as may happen to wander 

 within the precincts of its eddying vortex. 



Of specimens of Cordylophora detached from the timher- 

 baulks in the Victoria Docks in search of this Polyzoon, by 

 far the richer supply has been found adherent to that which 

 was taken some five or six feet below the surface of the 

 water, little, if any, being met with on such as from its 

 proximity to the surface was easily attainable with the hand 

 alone ; and this apparent partiality for deep water readily 

 accounts for the difficulty that has hitherto been experienced 

 in keeping it alive for any length of time in shallow vessels. 



The morphological affinities of Victorella pavida are some- 

 what remarkable. Overlooking, for a brief interval, the 

 structure of the polypidom, its relationship to various repre- 

 sentatives of the Vesiculariadae are at once palpable and 

 striking. Its possession of eight tentacula point out its affi- 

 nity to the genera Serialar'ia, Vesicularia, T alkeria, Mimosella, 

 and Bowerbankia, but the absence of a masticatory organ or 

 gizzard restricts the comparison to the first and third alone 

 of those five genera ; and happening to have at hand an 

 admirably prepared slide of J'alkeria pustulosa, with the 

 tentacles in a state of full expansion, I found that, except in 

 size, the latter being much the larger, any histological 

 difference between the two was difficult to determine. 



Of as high importance, however, as the various modifica- 

 tions of the endoskeletal system of ossification in the different 

 groups of the Vertebrate division of the animal kingdom, 

 must be ranked the structure of the polypidom or exoskeletal 

 system of support which obtains in that invertebrate section 

 of the same kingdom to which we are now referring ; and 

 here, as has been already demonstrated, there is a most 

 essential and important difference, and one which very few 

 words will suffice to show carries with it a peculiar and no 

 less important significance. 



The infundibulate arrangement of the tentacula and, above 

 all, the coronet of protecting setse at once suggest the neces- 

 sity of referring Victorella to a sub-order, — the Ctenostomata, 

 which has hitherto been known as having none other but 

 marine representatives; while, on the other hand, the irregular 

 and homogeneous structure of its polypidom is precisely what 

 we meet with in P/wma/e/Za and other members of an order, — 

 the Hippocrepia, of which not a single representative has 

 yet been discovered inhabiting pure sea-water, and hence the 

 sum total of the structural peculiarities of this minute denizen 

 of brackish water seems to go far towards furnishing us with 

 one link of a series which future investigation and comparison 

 may demonstrate to unite the two. 



