26 M. St-Hilaire 07i a Poli/dactt/hus Horse. 



. Bones of In Man. In Horse. 

 the shoulder, 2 1 The clavicles are wanting. 



Bo. arm, 1 1 



Do. fore-arm, 2 2 Only when the animal is young ; when 



old the ulna, which at all times in the 

 horse is an imperfect bone, becomes 

 firmly united to the radius. 

 Do, carpus, 8 7 The part of the limb corresponding to 



these bones is very generally, but very 

 improperly, called the knee. 

 Do. metacarpus, & 3 One complete and two incomplete, im- 



perfect, or rudimentary. 

 Do. fingers. 14 3 



Tlie horse, then, has but a single toe or finger, and not three, as 

 some anatomists have said. The extremely imperfect and ru- 

 dimentary metacarpal bones can never be called imperfect toes 

 in strict language ; nevertheless they really constitute the ele- 

 ments of toes, which have been formed in this imperfect and 

 rudimentary manner, because they were not wanted for the 

 safe progression of the animal, inasmuch as we apply this term 

 to the short toes of the pig, which have a metacarpal and digi- 

 tal bones, are detached and protected by a nail similar to the 

 more perfect or longer ones. On the contrary, all that remains 

 of such toes in the horse are two small perfectly rudimentary 

 metacarpal bones ; there is not the slightest vestige of any digi- 

 tal bones or phalanges. 



It sometimes happens, as may be seen in museums, that the 

 imperfect toes of certain animals (as in the pig for example) 

 occasionally are found perfect, or, in plain language, grow to 

 the same length as the more perfect ones, and of this we have 

 seen one or two instances in the pig, all four toes being in these 

 specimens of equal length and strength, or nearly so. Now 

 this seems to be the case with the foetus of the horse described 

 by M. St-Hilaire, and if so, as we doubt not, is the only in- 

 stance recorded, unless we consider as such the horse describ- 

 ed by Suetonius, and said to have belonged to Cassar ; but to 

 enable us to decide on this point neither the description of Sue- 

 tonius nor of the French naturalist, will be found sufficiently mi- 

 nute. M. St-Hilaire describes the foetus he examined to have 

 been about eight or nine months old. He states that it is poly- 

 dactylous only in the fore-feet ; and that the left foot has three 



