1905.] HARES FROM SOUTHERN SWEDEN. 281 



of each zygomatic arch is especially different in the two species. 

 In L. eitropceus the distance from the anterior end of the deep 

 groove for muse, masseter lateralis (portio profunda) to the 

 anterior vertical border of the arch itself is greater than the 

 height of the same portion of the zygomatic arch. In L. timidus 

 the condition is quite the ojjposite, the height of the anterior 

 portion of the zygomatic arch being greater than the distance 

 from the anterior end of the groove or fossa mentioned above 

 and the anterior boi-der of the arch. In the hybrid the condition 

 is intermediate, but nearer that of L. ti7niclus. The anterioi", 

 inferior angle of the orbit in the hybrid has a structui'e which, 

 singularly enough, differs from that of both parental forms. 

 In both the latter the jugale and the lower part of the 2^^'ocessus 

 spheno-orhitalis of the maxillary project in such a way that a 

 rather deep fossa is formed in the inferior anterior angle of the 

 orbit between the bones mentioned and the alveolar protuberances. 

 This fossa is, however, entirely missing in the hybrid. This 

 depends evidently upon a different arrangement of the insertion 

 of the muscles. In the parental foi-ms, to judge from my material, 

 the anterior portion of the masseter lateralis is confined to the 

 interior surface of the zygomatic arch and its upper margin in 

 the anterior corner of the oi'bit ; but in the hybrid it spreads 

 further forward on the facial area, where a tubercle and some 

 rugosities indicate the limit of its insei'tion. The difference be- 

 tween the hybrid and the parental forms indicates accordingly an 

 increase of a part of the masticating apparatus in the former. 

 The very great development of the whole zygomatic arch of the 

 same shows that other parts of the masseter as well have been 

 enlarged to a considerable extent. The greatest height of jugal 

 is in the hybrid 12'5 mm., while the greatest corresponding- 

 measurement for L. timidus is 10 mm., and for L. eurojiceus only 

 a little more than 9 mm., so far as my material goes. The fossa 

 pterygoidea in the hybrid specimen is larger (its width being more 

 than 8 mm.) than in either of the parental species, and its shape 

 is intermediate : thus the omisculits pterygoideus interims has a 

 wider area of insertion in the hybrid than in the parental forms, 

 and the great breadth of the lamina lateralis proves the same 

 for the m. pterygoideus externus. The sidcus temjwralis of the 

 squamosum has in the hybrid almost the same shape as in L. tim,i- 

 dus, that is to say deeper and narrower than in L. europceus. 



The supraorbital processes are very strongly developed in the 

 hybrid, but the frontal region of the skull behind the 2^'>'0cessus 

 supraorhitales p)osteriores is very strongly constricted, not measuring- 

 more than 13 mm. This, which is the more striking when the 

 great size of the skull is considered, I regard as an inheritance 

 from. L, eurojyaius ; as of ten skulls of L. timidus none is so narrow, 

 the limits of variation being 15-19 mm. and the usual dimension 

 17 mm. In L. eitropceus the same dimension is in my matei-ial 

 from 12 to 15 mm. 



