8 EVERS'S COMPARATIVE ANATOMY. 



or whether we make use of several, provided that our object of con- 

 veying or acquiring a knowledge of the comparative structure of 

 animal bodies be attained. This must be my excuse for appearing 

 in some places to have followed the arrangement of Cuvier, and in 

 others, that of Dr. Grant, both having their excellences, and their 

 authors holding the highest place as authorities on the subject. 



Cuvier's and Grant's classifications are therefore subjoined, ac- 

 companied by familiar illustrations of each, to lead the student at 

 one glance to the objects which each subdivision embraces. The 

 examples appended to Grant's classification have been added by 

 myself, whilst those of Cuvier have been taken from Dr. Houston's 

 Descriptive Catalogue of the Preparations in the Museum of the 

 Royal College of Surgeons in Ireland, with a few additional exam- 

 ples from Roget's Bridgewater Treatise. 



It might appear an omission not to make some allusion to the 

 arrangement of the animal kingdom adopted by the immortal Lin- 

 neeus, but the researches of later zoologists have proved it so defec- 

 tive, that it is not followed by any writer or teacher of the present 

 day, and needs therefore but a cursory allusion. Suffice it to state 

 that he divided the whole animal kingdom into six classes, Mam- 

 malia, Aves, Reptilia, Pisces, Insecta, Vermes, founding his classi- 

 fication mainly on the peculiarities afforded by the respiratory and 

 sanguineous systems. 



OUTLINE OF CUVIER'S CLASSIFICATION OF ANIMALS. 



FOUR GREAT DIVISIONS. 



1. Vertebrata. 3. Articulata. 



2. Mollusca. 4. Radiata. 



VERTEBRATA. 



Characters. — Internal skeleton — brain and spinal marrow in separate cavi- 

 ties — red blood and muscular heart — mouth with horizontal jaws — five 

 organs of sense — never more than four limbs — separate sexes. 



MOLLUSCA. 



Ch. — No skeleton — muscles all attached to external skin — nervous system 

 situated in the visceral cavity and composed of separate masses joined by 

 nervous filaments — taste, sight, or as in one instance, hearing, the only senses 

 — organs of circulation, respiration, and digestion very perfect. 



ARTICULATA. 



Ch. — No skeleton — two long nervous chords with ganglia at intervals — 

 have usually taste and sight — divided in jointed rings, soft or hard, to inside 

 of which muscles attached — sometimes lateral limbs, sometimes none — jaws 

 when present alwavs lateral. 



