Royal Microscopical Society. 97 



tissues are of an indiffererd kind. The result of this morphological 

 research appears to me to be the gathering together of a mass ot 

 evidence in favour of the theory of evolution. I have already 

 spoken of tlie stages of the fowl's skull, and what they point to ; 

 and I am at present engaged in working out the facial arches and 

 nasal capsules of carinate birds, generally, so that the paper on the 

 Fowl, with this supplementary work, may serve as a memoir on the 

 Bird's Skull, and not that on the Fowl, merely. What do I find ? — 

 that the whole group of existing birds, excluding those half-ostriches 

 the Tinamous, as well as the genuine ostriches, form a mere Order, 

 as neat and compact as the Lacertilia among the reptiles. Once a 

 small distance .above the ostriches, and the life-tree forks and re- 

 forks, and very few steps upwards have to be made before we arrive 

 at the most accomplished types. From that monster bird, the 

 Dinornis, to that feathered bee, the humming-bird, there are but 

 a few and easily-traced stages ; and from the ostrich, that plumed 

 camel, up to the most perfect birds of the group — 



I. 



"The ousel-cock, so black of hue, 

 With orange-tawny bill, 

 The throstle, with his note so true, 

 Tiie wren with little quill, 



II. 



" The finch, the sparrow, and the lark, 

 The plain-song cuckoo gray," — 



« * >): l|< 



The distance, I say, between that giant and these exquisite types 

 (by way of the tinamou, the hemipod, and the songless Passerines of 

 the New World) is very small indeed. Finally, for I fear you are 

 growing weary, the frog, after having passed its simple and pri- 

 mordial stage, passes into a state between the lamprey and the 

 chimsera, and then skipping past the osseous fishes and tailed Am- 

 phibia, foreshadows the mammal in its wondrous metamorphosis. 



As to the salmon, the simple stage once passed, it gets, even 

 before hatching, on to the level of the sharks and rays ; in a week it 

 is a Ganoid, and in a few weeks attains a sub-teleostean type — a con- 

 dition somewhat below the highest kinds of fish, such as the Percoids. 



It is said that proper Teleostean (osseous) fishes are not known 

 below the Chalk ; yet the Plagiostomes (rays and sharks) are found 

 with the Ganoids in the Upper Silurian deposits — the Plagiostomes, 

 however, being the lower types. All these things " atone together " ; 

 and, as far as we know at present, the life-history of each indi- 

 vidual of a high type is a repetition of the evolutional progress 

 in the ascent and modification of the vertebrate forms from the 

 Beginning. 



