OCR Text |
Show 274 MESSRS. 0 . THOMAS AND H. SCHWANN ON [Apr. 18, Incisors with their notch shallow, situated in a comparatively broad flattening of the front surface of the tooth. Laige upper molars and premolars (shown in Lyon's pi. xci. fig. 8) with the uncrenulated anterior enamel-wall of the posterior lamina of each tooth extending nearly halfway across the tooth towards the outer border; crenulated adjoining outer parts of the enamel-walls of the two laminae subequal in development, strongly crenulated. Anterior lower premolar with its anterior enamel-wall deeply crenulated. Thin front wall of the hinder lamina of each lower tooth (apart from m3) very strongly crenulated. In P. crassicaudatus, on the other hand, the skull is small, more slenderly built, the muzzle narrow, and the frontal profile flat. Supraorbital wings larger, their hinder edge closer to the brain-case. Anterior shoulder of zygoma small. Palatal foramina large, evenly broadened to their hinder edge, widely open behind, with slanting and scarcely ridged margins which do not hide the Avails of the nasal chamber below. Sphenoid openings comparatively large. Bullae fairly large, not surpassed by the small paroccipital processes. Incisors with a comparatively deep sharply defined notch dividing the two strongly convex portions of the anterior surface. Large upper cheek-teeth with the uncrenulated part of the anterior enamel-wall of tlieir posterior laminae extending only about a third across the tooth ; in the crenulated part of the enamel-walls the hinder wall of the anterior laminae is considerably more developed than the front one of the posterior, and all are less strongly crenulated than in P. ruddi. Anterior lower premolar simply notched in front. Front wall of the hinder lamina of the large lower cheek-teeth scarcely crenulated. It will thus be seen that while externally P. ruddi is very like P. crassicaudatus, the differences in the skull are so considerable that almost any par t of the skull, or any single tooth, can be readily assigned to one or the other. Dimensions of the type of P. ruddi (measured in the flesh):- Head and body 482 mm.; tail 52 ; hind foot 99 ; ear 98. (The hind foot of P. crassicaudatus is seldom over 80 mm.) Skull-greatest length 92; basilar length 72 ; zygomatic breadth 40 ; nasals 44 x 22 ; interorbital breadth 16 ; intertemporal breadth 13*3; diastema 30; palatal foramina 26 x 8‘5 ; palatal bridge 9'7. Corresponding measurements of two members of the P. crassicaudatus group are to be found in Thomas's descriptions of P. c. nyikce and P. c. curryi *. Hub. Sibudeni, Zululand. Alt. 1100 m. Type. Male. B.M. no. 4.5.1.78. The discovery and elucidation of this remarkably fine hare is a valuable result of Mr. Rudd's exploration of S. Africa, and one of special interest, as it forms a second species of the recently erected genus Pronolagus. * Ann. Mag. N . H. (7) x. pp. 245-6 (1902). |