194 Thomas — Nomenclature of Measurements. 



the Englisli word basal by the older writers, such as Flower and 

 ()th(a-s, who used the measurement from the giiathion; while 

 basilar is an adaptation of the German of Hensel and his school, 

 who used the '' Ixjsilar-langc" from the henselion. These 

 names again, coml)ined with condylo-, readilj^ express the points 

 which are used by those who like to adopt the condylion as a 

 posterior measuring point. 



But further, the association of the ending " al " witli a meas- 

 urement from the gnathion, and " ilar " with one from the 

 henselion, if once defined and fixed, may l)e utilized in a second 

 case of similar character. 



The length of the l)ony palate is a measurement given l)y all 

 careful descril)ers, but the anterior measuring point used is again 

 either the gnathion or henselion, doul)t as to which is being 

 used often nullifying the value of the measurement altogether.* 

 To avoid this doubt I would suggest, exactly as in the other 

 case, that tlie name of the measurement from the gnathion 

 should end in " al " and that from the henselion in "ilar." 

 We should then liavc: 



Palatal len'(;tii, the distance from gnathion to palation. 



Palatilah lkxctu, the distance from henselion to palation. 



The indeterminate " palate length " would then be dropped 

 altogether. 



II. The Names of the Cheek-teeth of Mammals. 



Although the cheek-teeth of mammals, the molars and pre- 

 molars, have l)een studied and written about ever since the birth 

 of zoology, no uniform system of naming them has l)een evolved 

 and there is the gi'eatest divergence between the usage of differ- 

 ent workers on the sul)ject. In old days all were called molars 

 or grinders; then the j)remolars were distinguished from the 

 true molars (although French zoologists, Winge in Denmark, 

 and Ameghino in Argentina, continued to use a continuous 

 notation for the two sets of teeth combined) and the usual habit 

 among zoologists in general was to speak of them individually 

 as " second preiuolai'," "third molar," and soon. ICven here, 

 however, an important difference cropped up owing to Hensel 



* I may explain that in my own descriptions the palate of any given animal has al- 

 ways been measured from the same anterior point, gnathion or henselion, as the skull 

 itself, this latter being indicated by the use of the words basal or basilar. 



