and its Siynificance in Systematic Zoology. 91 
and anal aperture besides. But it must be borne in mind that 
the anus in the Polyzoon does not open at the extremity of the 
body opposite the mouth, as in the archetypal Mollusc, but, by 
a sudden bend of the intestine, the anal aperture is brought into 
the closest possible proximity to the mouth, so that, although 
separate, they both open at the same spot. And let it not be sup- 
posed that this detracts aught from their position as Molluses ; 
for in the highest Molluscs, viz. the Cephalopods, the same thing 
takes place in a somewhat less degree. Here, again, is a structure 
which implies great community of general habit. Lastly, there is 
another most important community of habit between the Polypes 
and Polyzoa, viz. that, although the Mollusca as a class are ovi- 
parous, the Polyzoan Molluscs are, in addition, gemmiparous, like 
the Polypes ; and this power is evidently the secret of the pro- 
duction of those compound forms which the Polyzoa present in 
common with Polypes. Hence we see that, with scarcely anything 
in common except superficial characters, the habits of Polyzoa 
and Polypes are nearly identical ; and to this fact I would look for 
an explanation of their identity of form. 
XV.— Observations on two new species of Chiton from the 
Upper Silurian ‘ Wenlock Limestone’ of Dudley. By M. L. 
De Konrncx, Member of the Royal Academy of Sciences, 
Belgium, &c.* 
[With a Plate. | 
On my last visit to England I had the opportunity of studying 
a great number of new fossils, forming part of the magnifi- 
cent collection of Mr. John Gray of Hagley, amongst which I 
observed two species of Chiton, obtained from the Upper Silurian 
__ beds of the neighbourhood. 
Before entering into a detailed description of these species, it 
would perhaps be useful to give a résumé of the paleontological 
works which treat of species of a similar character to those form- 
ing the subject of these observations. 
Genus Carron, Linn. 
Established by Linnzus in 1758 for a small number of living 
species, this genus for a long time had no representative amongst 
fossils. 
It was not until the year 1802 that the first species of fossil 
* Translated by W. H. Baily, F.G. S., Acting Palzontologist to the 
Geological Survey of Ireland, from the ‘ Bulletins de l’Académie Royale 
des Sciences, ete. de Belgique,’ 26"° année, 2™° sér., t. iii, 1857. 
