1871.] 309 [Wilder. 



Fish, for which the thanks of the Society were voted to the 

 donor. 



A paper was read by title " Observation on the Surface 

 Geology of North Carolina, by L. S. Burbank." 



INTERMEMBRAL HOMOLOGIES. By BURT G. WILDER, M.D. 



Continued from p. 188. 



IV. THE MORPHOLOGICAL UNIMPORTANCE OF 



NUMERICAL COMPOSITION. 



The familiar fact that with most Mammalia the pollical and primal 

 phalanges are only two in number, while the other digits and dactyls 

 possess three, forms the chief difficulty with those who are asked to 

 consider pollex the meketrope of quintus and primus that of minimus; 

 and it forms the only difficulty with those who have already recog- 

 nized the fallacy of the objections generally urged upon the ground 

 of the size and natural attitude of the parts; evidently then, the 

 removal of this difficulty is of the utmost importance. 



Here, as generally throughout this paper, the facts and conclusions 

 will be given with reference to the Mammalia; partly because that 

 class has afforded me the most material, but chiefly because the 

 three grand difficulties already mentioned are especially manifest in 

 the higher vertebrates; and I am convinced that they never would 

 have prevented our recognition of meketropy in the membra, had we 

 been lizards or turtles instead of primates. 



It cannot be denied that some significance must attach to numer- 

 ical composition of organs; since, aside from the symbolic character 

 which many believe them to possess, the very constancy of numbers 

 is a remarkable fact in Natural History. But for the general rule 

 that the mammalian cervix consists of seven vertebras, it is prob- 

 able that no effort would be made (as by Thomas Bell, Trans. Zool. 

 Soc, vol. i)to show that Bradypus tridactylus has but seven, instead of 

 nine, as believed by Turner and Owen; and there would be nothing 

 strange in the fact that Chokepus Hoffmann i has but six cervical verte- 

 bras; on the other hand, the value of this as even a generic character 

 seems to be destroyed by the fact, that another species of the same 

 genus (C. didactylus) has the usual number. 



Again, it is stated by Mosely and Lankester, that the mole is the 

 only placental mammal with eight intermaxillary teeth; and the ex- 



