SKULLS OF OXEN FROM NEWSTEAD, 273 



occiput viewed from behind is nearly straight, in otliers it is 

 slightly concave or distinctly arcuated. 



In specimens of the TJvus with veiy thick horn-cores a bi-idge of 

 bone extends downwai-ds from the base of the horn-core a,nd forms 

 a posterior wall for the temporal fossa (text-figs. 81 &■ 83, y.), which 

 completely cuts off' the fossa, from the occiput. It is owing to the 

 temporal fossa? being closed in behind by extra supports for the 

 horn-cores that the width of the occiput immediately below 

 the horn-cores is sometimes nearly twice as much as the distance 

 between the crest and the lower border of the foramen magnum. 



Though in the majority of the !N"ewstead skulls the occiput 

 conforms to the Urus type there are several with short premaxilla? 

 in which the occiput reminds one of Lydekker's Bos acutifrons. 

 Writing in 1880 Lydekker pointed out that Bos acutifrons of the 

 Punjab Siwaliks had no marked I'elationship to any existing species 

 and was " widely difiei-ent in the form of its occiput, frontals, and 

 horn-coi'es from Bos 2)rimigen,ius" * . 



Though Riitimeyer and others vegA.Yy{Q({ Bos 2)lanifrons and^os 

 acutifrons iia varieties of a species closely allied to Bos primigenms, 

 no skulls of true Oxen have hitherto been described in which the 

 occiput resembles that of Bos acutifrons. 



In Bos Qiamadicus, SiS well as in Bos 2^)' imi genius, the notches 

 below the bases of the horn-cores are shallow, but in the jS!"ewstead 

 skull represented in text-fig. 84 indentations or notches (iV".) 

 below the horn-cores are so deep that the connection between the 

 upper (parieto-frontal) part of the occiput and the lower (infra- 

 cristal) part is relatively short. Because of these indentations the 

 occiput viewed from behind (text-fig. 84) bears a resemblance to 

 that of the Gaur (Bos gaurus). 



In Bos primigenius the summit of the occipital cxest is on a 

 lower level than the middle of the horn-cores (text-fig. 83), 

 but in the Newstead skull of the acutifrons type a line carried 

 through the summit of the rounded arch formed by the occipital 

 crest (text-fig. 84) passes above the middle of the horn-cores. 



At the widest part the occiput of the first century skull 

 (text-fig. 84) measures 215 mm., and from the lower border of 

 the foramen magnum to the occipital crest the distance is 

 115 mm. The depth (115) multiplied by 100 and divided by 

 the width (215) gives an index of 53"5. In the Urus represented 

 in text-fig. 85 the corresponding index is 47. Between the 

 notches under the horn-cores the distance in the Newstead 

 skull (text-fig. 84) is 123 mm.: 123x100-^-215 (the total 

 width of occiput) gives an index of 57 ; in the Urus, owing to the 

 shallowness of the notches under the horn -cores, the correspond- 

 ing index may be 90. The distance (115 mm.) between the 

 lower border of the foramen magnum and the occipital crest 

 multiplied by 100 and divided by the distance (123 mm.) between 

 the infi-acornual notches gives an index of 93*5 ; the correspond- 

 ing index in the Urus may be only 52*4. 



* Memoirs of tlie Geological Survej^ of India, series x. vol. i. p. 2. 



