236 



KNOWLEDGE 



[OcTOIiKR 1, 1890. 



basis of classification of birds ; as is abundantly proved by 

 the number of totally diftVrent systems which have re- 

 sulted from the adoption of this method by various writers. 

 At the conclusion of this section tlie author mentions that 

 the oruitholosical system is still in a transition state, and, 

 apparently on this ground, he gives no system of avian 

 classification at all — an omission which we regard as an 



Fig. 1. — Boxes of Right Leg of a Dick. ' /•';». femur ;«, head of 

 do. ;^, liliiila ; It, tibia; ml, mctatai-i>us ; It-it, the four toes ; 1-5, 

 joints of do. ; A, hip ; B, knee ; C, ankle ; D, base of foot. 



error of judgment. Indeed, when we refer to the alterna- 

 tive title of the volume, this omission forcibly reminds us 

 of the celebrated chapter on Irish snakes. 



In treating of the structure of birds, the author com- 

 mences with the external characters, and then proceeds to 

 the consideration of their internal anatomy. Feathers are 

 described in full detail, with excellent illustrations, and 

 especial attention is given to the important subjects of 



Fig, 2. — Incessohiai. Foot of 

 A Passeiuxk Bird. 



Fig. 3. — Weisbed Foot of 

 Pelican. 



" pterylosis," the acquisition of the permanent plumage, 

 and its periodical changes. In the description of the 

 wings and ieet we find lucid explanations given both of 

 the exterior features and of the structure and mutual rela- 

 tions of the bones, the illustration fin page 159 showing 

 at a glance the homologies of the various bones of a bird's 

 wing with those of the fore limbs of mammals. In the 



figure of the bones of the leg of a duck, which we repro- 

 duce, the author not only directs our attention to the 

 indiviihial bones, but also points out the joints correspond- 

 ing to the human tliigli, knee, and ankle. The absence 

 of a series of free small bones in the ankle-joint of a bird is 

 fully discussed ; the complete union of the upper series of 

 ankle-bones with the leg-bone, and of the lower ones with 

 the three conjoint metatarsals being shown to be simply 

 one step in advance of the reptilian type of structure, 

 w-hich differs from that of mammals by having the ankle- 

 joint between the upper and lower rows of ankle-bones, 

 instead of between the upper row and the leg-bone. 



As their extreme importance demands, detailed and well 

 illustrated descriptions are given of the characters of the 

 various ij^es of the feet of birds, pointing out the modifi- 

 cations adapted for the different duties they have to per- 

 form. It is thus pointed out that the feet of birds are 

 chiefly modifications of three main types. Firstly, we 

 have the " incessorial " type, as exemplified by the Passe- 

 rines (Fig. 2), and aberrantly by the birds of prey. The 

 second type is the " cursorial," as displayed in fowls and 

 waders, while the last type is the swimming. The swim- 

 mmg type may present itself either as the fully-webbed 

 foot of a Pelican (Fig. 52), or of a Duck, or in the curiously 



lobate foot of a Coot 

 (Fig. 53), in which 

 each joint of the 

 toes has its own 

 special flap of integu- 

 ment. 



In treating of the 

 general osteology, 

 we notice that the 

 author proposes the 

 new term nacnirium 

 for that part of the 

 skeleton usually 



known as the sacrum, 

 but of which only 

 a small portion cor- 

 responds to the sac- 

 rum of a reptile. We are, however, doubtful w'hether this 

 proposed change is of any advantage. The illustrations 

 and descriptions of the base of the skull given in the 

 succeeding pages will enable the student to readily com- 

 prehend the principles on which Prof. Huxley established 

 his well-known classification of birds ; but liere again we 

 regret the coarseness of the figures. 



Of the soft inner parts the detaOs given are generally 

 more brief than those of other structures, this brevity 

 being carried to an extreme in the case of the muscles ; 

 indeed, it appears hardly fair to the labours of the late 

 Prof. Garrod to dismiss his elaborate work on the femoro- 

 caudal muscles with the bare mention given on page 289. 

 We are glad to see, however, fuller attention directed 

 (page 293) to this writer's researches on the curious modi- 

 fications assumed by the carotid arteries of the various 

 groups of birds. 



In endeavouring to place the popular study of birds on a 

 sotuid anatomical basis, Professor Coues has done good 

 service to science, and it may be confidently said of his 

 work that it is the only one in the English language in 

 which the student will find in a convenient and accessible 

 form all details of both external and internal structure that 

 are necessary to enable him to grasp the general principles 

 of avian organisation. In conclusion, we venture to 

 hope that the English edition of his work may attain a 

 success like that which appears to have crowned its 

 American forerunner. — R. L. 



Lobate Foot of a Coot. 



