0)1 new Heterocera from Dutch JS^eio Guinea. 205 



Gisburn, Yorks. This specimen is also in the Miinchester 

 Museum, and the lower jaws have the usual six teoth. 



Comparing a number of five-toothed jaws with a like 

 number of six-toothed jaws, there seems to be a general 

 tendency for all the teeth in the latter form to be somewhat 

 smaller, as will be seen by the table on p. 294:. 



It niio-ht here be mentioned that there is nothinor in the 

 Glastonbury bones and lower jaws to indicate that more than 

 the one species is present, viz. Bos longifrons. 



Unfortunately in most finds the exact relation between the 

 upper and lower teeth cannot iisually be ascertained, owing 

 to the scattered and imperfect condition of the remains. It 

 might be of interest, therefore, to point out that the asso- 

 ciated upper and lower jaws were found of the Haverbrack 

 S[)ecimen, and tiiese sho\v the six teeth of the upper jaw 

 exactly opposed to the five lower teeth ; so tiiat, if '^^^^i were 

 present, it would be quite fuiictionless. 



The whole feature of the loss of ^^^ in some oxen jaws 

 seems to me to be a clear case of degeneration gradually 

 brought about by disuse of that particular tooth. 



Though the absence of ^^^ ''^ ox jaws has betn known for 

 some time, the absence of this tooth from the jaws of sheep 

 does not appear to have been noted hitherto. On sorting the 

 sheep-remains from Glastonbury, however, I came across a 

 fair percentage of lower jaws with only two premolars and 

 three molars present in place of the usual six teeth. 



This feature, as in the ox, may be likewise due to disuse, 

 probably through change of food or habit under domestication. 



As a further instance of ^5775 being missing, I might men- 

 tion that both lovver jaws of a specimen of Oapra ibex in tlie 

 Manchester Museum possess only five teeth. 



XXIV. — JSeio Species of Heterocera from Dutch Neio Guinea. 

 By J. J, JoiCEY, F.L.S., F.E.S., and G. Talbot, F.E.S. 



[Plate XII.] 



The following species were all collected by Messrs. A. C. 

 and F. Pratt in the Arfak Mountains, Dutch New Guinea, 

 and the types are in the collection of Joicey. We are 

 indebted to the Hon. W. Rothschild and Sir Geo. H, Kenrick 

 for the opportunity afforded of comparing specimens in their 

 collections. 



20* 



