CARPENTER ON FORAMINIFERA. % 185 



set of nerves to muscles, and of another to the skin ? Clearly the latter ; 

 for there is nothing in the nature of the nerve tissue itself to prevent its 

 serving both functions, as we see in the animal which has only one nerve 

 for both : this nerve is not, as in vertebrata, split up into two, having 

 two different origins, and two different peripheral terminations, but is 

 one nerve, with one origin, sending off branches, here to muscles, and 

 there to surfaces. 



In his memoir on the Haliotis, M. Lacaze-Dnthiers notices that the 

 optic nerve has two kinds of branches, "les uns, que Ton pourraitnom- 

 mer tegumentaires, et les autres oettfo/m proprenient dits. Les premiers 

 se distribuent aux teguments et aux tissus contractiles de nature mus- 

 culaire qui forment les parois du tubercle ; evidement ils apportent et 

 la sensibilite et la motilite a ce support de 1'organe de la vision." He 

 notices as remarkable, that from the very trunk of a nerve of special 

 sense, branches are given off, which are nerves of general sensibility 

 and nerves of motion. But he contents himself with the supposition 

 that there may be sensitive and motor fibres in this trunk, separate at 

 their origin, though combined together in the trunk. This is, how- 

 ever, irreconcileable with microscopic observation of the molluscan 

 nervous system ; for when there are fibres, they are nothing but linear 

 arrangements of the granular mass filling the neurilemma, which enter 

 the ganglion together, and not from separate parts corresponding to 

 anterior and posterior horns. 



I will not extend this paper further, by any attempt to assign more 

 definitely the functions of the nerves. The question at issue is : Are 

 we justified in denying a sensory function to the anterior nerves, and a 

 motor function to the posterior nerves ? Is the difference between them 

 one of property, or of function ? 



XIX. — General Results of the Study of Typicax Forms of Forami- 

 nifera, in their relation to the systematic arrangement of 

 that Group, and to the Fundamental Principles of Natural His- 

 tory Classification. By William B. Carpenter, M.D., F.R.S., 

 F.L.S., F.G.S. 



Having been for some time engaged in the study of a series of typical 

 representatives of several of the chief natural divisions of the Foramini- 

 fera,** and finding that the general results of my inquiries are fully 

 borne out by the study of other types prosecuted on the like method by 

 Messrs. Rupert Jones and W. K. Parker, I think it desirable to draw 

 the attention of naturalists to them, not merely as fixing the principles 



* See my Researches on Foraminifera, first and second Series, in the Philosophical 

 Transactions for 1856; third Series, op. cit., 1859 ; fourth Series, op. cit., 1860. 

 VOL. I. — N. H. R. 2 B 



