2780 Zoological Society. 



March 12. — William Spence, Esq., F.R.S., in the chair. 



The Secretary read the first part of a paper, by Prof. E. Forbes, descriptive of the 

 new Mollusca collected by Capt. Kellett and Lieut. Wood during the surveying voy- 

 ages of H.M.S. Herald and Pandora, chiefly on the West Coast of Central America. 



The Secretary also read a paper entitled " First Thoughts on a Physiological Ar- 

 rangement of Birds," by Mr. Newman ; and intended as an introduction to an entire 

 revision and re-classification of this interesting division of the vertebrate animals. 

 The author began by observing that 



The systematic arrangement of the Class Aves is more unsettled than that of any 

 other portion of the Animal Kingdom, — a circumstance that may fairly be attributed 

 to our attaching too high a value to characters purely structural or admensural, while 

 we neglect others more intimately connected with reproduction ; in a word, to the 

 substitution of physical for physiological characters. In mammals, reptiles and 

 fishes, we have a primary division based entirely on physiology: thus mammals are 

 placental or marsupial ; reptiles are oviparous or spawning ; fishes are viviparous or 

 spawning ; and this primary division of these classes is admitted by all physiologists 

 to be strictly natural. Notwithstanding, however, the purely physiological characters 

 on which these primary divisions depend, it is found that physical characters harmo- 

 nize with physiological, and that intimate structure in each instance bears out physi- 

 ological difference. It were not wise altogether to discard structural differences, even 

 in the outset of an inquiry into system, but it is necessary to use them rather as cor- 

 roborative than as indicative, and, above all, to draw a distinct and permanent line 

 between such as are truly intimate and such as are purely adaptive. It has always 

 appeared to me that one of the chief advantages of an extensive vivarium like that 

 possessed by our Society, is the opportunity it affords for studying animated nature in 

 an animated state, for ascertaining physiological as well as physical characters. If, 

 then, we avail ourselves of the opportunities which are or ought to be thus afforded 

 us, we shall find that in the very outset of life a physiological character of the most 

 obvious kind will divide birds into groups as distinct as are the placental and marsu- 

 pial mammals, or the cartilaginous and bony fishes. Prior to the extrusion of the 

 egg, observed facts bearing on this subject are so few and so unconnected that they 

 cannot be rendered available as affording evidence on the question to be considered : 

 it is therefore compulsory that our comparisons begin at that moment when the con- 

 dition of the young becomes patent by the breaking of the shell. Commencing the 

 inquiry at this point, which may safely be regarded as analogous to the birth of a 

 placental animal, we have these obvious grand divisions of the class :— 



1. Hesthogenous Birds. In these, immediately the shell is broken the chick makes 

 its appearance in a state of adolescence rather than infancy : it is completely clothed, 

 not with such feathers as it afterwards wears, but still with a close, compact and warm 

 covering. It possesses the senses of sight, hearing, smelling, &c, in perfection : it 

 runs with ease and activity, moving from place to place at will : it perfectly under- 

 stands the signals or sounds uttered by its parent, approaching her with alacrity when 

 invited to partake of food she has discovered, or hiding itself under bushes, grass or 

 stones, when warned of danger, — in either case exhibiting a perfect and immediate 

 appreciation of its parent's meaning ; it feeds itself, pecking its food from the surface 

 of the earth or water, and not receiving it from the beak of its parent : although en- 

 tering on life in this advanced state, it grows very slowly, and is long in arriving at 



