Proceedings of the Jfernerian Society. 213 



cal classes, and that, whenever two groups of any ranks are structurally 

 and formally equal, one will be found to represent the animal sphere, and 

 one the vegetative. To ascertain the true sources of character on which to 

 base the various groups of the mollusca, that type must be viewed gene- 

 rally ; 1st, in regard to the whole animal kingdom; and, 2d, per se as 

 typical of some great function. In the first point of view, they represent 

 the progression towards a cerebral concentration of the nervous system, 

 and accordingly the highest divisions of the type must be derived from 

 that system ; in the second, they represent the function of respiration, 

 since they exhibit all the modifications of the respiratory system, and from 

 that system must be derived the ordinal divisions. The shell of the true 

 mollusca is a modification of the dermato-skeleton for the express protec- 

 tion of the respiratory organs, and accordingly it plays an important part 

 in the true arrangement of the order. The shell of the cephalous mollusks 

 is of a very different nature, and owes its form and structure to the posi- 

 tion of the shelled cephala in the parallel of annulism, it being an articu- 

 late shell, representing the testaceous covering of the foramenifera. 



The hypothetical arrangement of the classes and orders of the mollusca 

 resulting from this view may be expressed as follows : — 



MOLLUSCA. 



Classical Xumber. 



Cephala, 

 Paracephala, 



ACEPHALA, 



{ Pulmonifera, 

 -! Phyllobranchiata, 

 ( Pectinibranchiata, 

 ( Lamellibranchiata, 

 1 Palliobranchiata, 

 ( Heterobranchiata, 



Ordinal Number 

 1 

 1 

 1 

 1 

 1 

 1 

 1 



There was then read a notice by Mr John Balfour of Toronto, Upper 

 Canada, on the so-called Sulphur Showers of the Canadas and United 

 States, and a specimen was exhibited. Dr Neill read a communication 

 from Mr MacGillivray, stating that the Pink-footed or Short-billed Goose, 

 Anser brachyrhynchus, occurs occasionally on the stalls of our poultry 

 market, and is generally mistaken for the Bean Goose, Anser segetum. 

 That species, however, is distinguished by very marked characters, and 

 is the most common with our poulterers ; the true Grey Lag, Anser palus- 

 tris, of Ray and Dr Fleming, being of rare occurrence. It is but very 

 recently that the short-billed goose has been clearly distinguished ; and 

 this, together with other occurrences of a similar nature, ought to shew 

 that such characters as ' head and neck brown, upper parts grey, lower 

 paler, tail of sixteen feathers,' which are common to several species, are 

 not sufficient to enable one to determine the species of a bird that he may 

 have procured. The peculiar habits of the present goose arc as yet little 



