186 Mr. Touhnin Smith on the Ventriculidie 



essential aid towards determining the proper position and true 

 affinities, of the animal to which they belonged. It will be ob- 

 served that these processes are affixed to the strict polypidom, not 

 to any distinct and separable external cell, thus adding another 

 to the many evidences afforded by the Ventriculidae that the 

 whole of every polyzoic polyp-mass is a true entire animal, of 

 which the polypidom forms but one essential and inseparable 

 part. 



The last observation leads naturally to the inquiry — if the 

 moveable processes are not attached to any distinct and separable 

 external polyp-cells*, as in Membranipora, Eschara, &c, have 

 any traces of the existence and position of the polyps been dis- 

 covered ? Now it is undoubtedly the fact that the surface of the 

 vast majority of these fossils exhibits no trace of polyp-cells. 

 And remembering that many of the most highly organized of 

 the recent Polyzoaf present very faint external traces of cells 

 when dead, I had little hope of ever finding absolute evidence of 

 the presence of those cells in the Ventriculidae. Even in the 

 Escharidse they are often obliterated, while in the Halodactylus 

 diaphanus it is rarely that they can be traced in specimens pre- 

 served in spirits. Even in the recent animal they can only be 



* The separateness, externally, of the polyp-cells is a matter more appa- 

 rent than real. The Ventriculite cells were quite as individually separate, 

 the independence of each other, therefore, of their inhabiting polyps at least as 

 great, as in Eschara, Flustra, &c. ; indeed more so, there being in the former 

 a distinct extent of the underskin between each. In the Halodactylus dia- 

 phanus the cells merely assume a hexagonal form " from their pressure upon 

 each other." This is very inferior to the Ventriculidae : see Farre's paper 

 above-cited, p. 409, and above, p. 1 80. Space forbids me to enter so fully into 

 this subject as I could wish, and as its importance might render desirable 

 were it not that the line of argument would be thereby interrupted. 1 will 

 do no more now than recall the reader's attention to the fact of the organized 

 external integument common to the compound Ascidians, which the under- 

 skin of the Ventriculidae certainly resembles more than does the connecting 

 medium of the Eschara ; and to two quotations from Dr. Johnston (Zoo- 

 phytes, p. 255 — 257) bearing directly on the point. "The cell," he says, 

 " is in fact the outer tunic of the polyp analogous to the envelope of the 

 compound mollusca, * * in organic connexion with the interior parts, and 

 liable to organic changes;" and in distinguishing by a marked character the 

 Polyzoa from the Anthozoa, he says, " Jn the latter the polyps are simply 

 developments of the common central fleshy mass, identical with it in struc- 

 ture and texture; in the former each individual is a distinct organism, and 

 the medium which binds them together, whether vascular or ligamentous, 

 has its own peculiar character." If this is correct, there can be no doubt 

 that the Ventriculidae answer to the second description and not to the 

 first, and that indeed in a much more marked manner than do Eschara, 

 Flustra, &c. 



f I use the term Polyzoa in preference to Bryozoa, first, as having a prior 

 title, second, as having some significance, which Bryozoa has not. It is quite 

 enough to perpetuate error by calling an order animal plants, without in- 

 creasing it by calling one class of that order " moss-animals " ! 



