22 



RECAPITULATION. — Amphibia. 



1. In amphibia rudiments of ribs only are met with. 



2. Vertebrae range from eight in the rana pipa to eighty-nine in 

 the siren. 



3. In the frog, the extremities, especially the posterior, are fully 

 developed ; the tail is absorbed. 



4. Salamander, proteus, and siren, may be well contrasted with 

 the frog ; in the former the spinal column attains and maintains a 

 high degree of development, whilst their members are reduced to a 

 mere rndimental type. 



5. The bones of the cranium remain loosely united through life. 



6. The os hyoides undergoes remarkable changes during the 

 metamorphosis of the animal from the pisciform to the reptile 

 state. 



recapitulation. — Reptilia. 



1. The vertebrae and ribs are more numerous" than in any other 

 class of animals. 



2. The chelonia differ from the sauria in having immovable ribs, 

 and from the ophidia in having arms and legs. 



3. The bones of the head generally maintain a permanent state 

 of separation, except the parietals which are firmly auchylosed. 



AVES. 



As in this department of my subject I avail myself of much of the 

 valuable matter contained in the article, Aves, in the Cyclopaedia of 

 Anatomy and Physiology, by that clear, accurate, and scientific 

 writer, Mr. Owen, it becomes necessary to state that he divides the 

 class into the following orders : — 



1. Raptores, birds of prey, or raveners ; 2. Insessores, perchers ; 

 3. Scansores, climbers ; 4. Rasores, scratchers ; 5. Cursores, 

 coursers; 6. Grallatores, waders ; and 7. Natatores, swimmers. 



Positive characters of the class. — Animal, vertebrated, oviparous, 

 biped: anterior extremities organised for flight; integument plu- 

 mose ; blood red and warm ; respiration and circulation double ; 

 lungs fixed and perforated. 



Negative characters. — No auricles, teeth, lips, epiglottis, dia- 

 phragm, fornix, corpus callosum, or scrotum. 



The bones of birds are remarkable for being permeated by atmo- 

 spheric air, for their compact and laminated texture, their white 

 colour, and their fragility, owing to a preponderance of phosphate of 

 lime. 



The vertebrae are the first bones observed in the development of 

 the osseous system of birds, and of all parts of this system, they 

 present the fewest variations. The spine here consists of cervical, 

 dorsal, sacral and caudal portions. The first and last are the most 



