French National Institute. 87 



The fusts of the former are thinner, and crooked from front 

 to rear ; those of the rest are crooked towards the palate : 

 this curvature distinguishes them from the front grinders, 

 whether they are the milk teeth* or those which succeed 

 to them, which are straight. 



The former of these back grinders are visible in the al- 

 veolus at the time of birth ; they come out at nine months, 

 and last all the life of the animal : they have also more 

 length for wearino; down hv mastication than all the rest. 

 The first and second have behind a small longitudinal ridge, 

 which assists them in cutting the alveolus, but which is 

 speedily followed by a plane surface destined to support 

 the tooth which comes from behind. The third back tooth, 

 on the contrary, not being to be followed by any other 

 tooth, preserves its ridge throughout its whole length j but 

 it has a small swelling which hinders 'it 'from opening the 

 alveolus so rapidly as the others. All these teeth, in deve- 

 loping themselves, cause upon the jaw the effect of an ex- 

 pansive instrument, which dilates it unequally, and varies the 

 form of it according to the age of the animal and conform- 

 ably to the wants of every period i)'i life. 



It is only by thus studying nature, in the minutest details 

 of her works, that we are competent to admire them as we 

 crught ; but how difficult is the studv ! The description of 

 the horse alone, has occupied the attention of M. Tenon for 

 these iTiany years. 



The same respectable anatomist has also recently pub- 

 lished the first volume of his " Recberclies cV Anatoynic et 

 da Ckirurgic." He principally treats of the eves, their dis- 

 eases, the ^'xfoliation of the bones, and he has inserted se- 

 veral of the memoirs which wc have noticed in our former 

 reports. This work, destined for men of science, cannot 

 be sufficiently analysed in a report of thi« n.it'.ire. 



M. Cuvicr continues his researches imu tho origin of those 

 animals whose skeletons the rcvolutioris of the earth have 

 brought to light, 



* Those which make their appearance when the animal is sucklinj?. 



F 4 M. de 



