1910.] Characters of Oryderopus. 335 



milk teeth were braehyodont with two roots (c/. Thomas, 1890).^ The 

 premaxUlnries are widely separated from the frontals; the nasals spread 

 proximally; the lachrymal is large, spreading on the faee; the lachrymal 

 foramen is external ; the orbital and temporal fossae are very near together 

 and broadly continuous {cf. Manis, Tupaia, Rodents); the orbito-sphenoid 

 is pierced by the optic foramen and the stapes by the stapedial artery (Weber, 

 1904, p. 41()); an alisphenoid canal is present; the tympanic is ring-shaped, 

 but there is no bony entotympanic (contrast Xenarthra, Van Kanipen, 1905, 

 p. 467); a tympanohyal is present (absent in other Edentates — Parker, 

 quoted by Weber, 1904, p. 415); the malleus has a broad lamina and a stout 

 processus gracilis (folianus) as in Sorex and Marsupials; in other features it 

 approaches that of Prioclon (Doran, 1879, pi. 64, fig. 14); the bicrural stapes, 

 as in many primitive mammals, is pierced by the stapedial branch of the ento- 

 carotid (Hyrtl, quoted by van Kampen, 1905, p. 467); the interparietal is 

 prominent; the mastoid is well exposed posteriorly; the occipital condyles 

 are confluent across the basioccipital. The vertebral zygapophyses are nor- 

 mal, the transverse process of the seventh cervical vertebra is pierced by 

 the vertebral artery {cf. Marsupials and certain Rodents); the dorso-lum- 

 bars number 21 (D 13, L 8); only the first sacral vertebra has the transverse 

 process broadly expanded for the support of the ilium-, the latter has a big 

 pectineal process and a prominent postero- superior extension (which Broom, 

 1905.4, homologises with the posterior angle of the ilium in Theriodonts). 

 The scapula has a large coracoid process and bifid acromion, the clavicle is 

 well developed. The humerus retains an entepicondylar foramen and 

 prominent crests; the radius and ulna are capable of more or less pronation 

 and supination; the ulna has a stout shaft; the femur retains a stout third 

 trochanter. The feet are semiplantigrade, the pes is pentadactyl. The 

 astragalus diverges distally from the calcaneum; it is pierced by a large 

 foramen and has a well grooved trochlea; the relations of its ectal, sus- 

 tentacular and navicular facets are much as in Phenacodus, but the head is 

 globular instead of flattened. The entocuneiform is long as it is in many 

 Insectivores and Rodents. 



Specialized characters. These underlying primitive characters are com- 

 bined with specializations characteristic of the order. The milk dentition is 

 vestigial {cf. Broom, 1909, and Thomas, 1890). No trace of incisors re- 

 main in the adult. The antemolar teeth drop out in old animals; they 

 are much less specialized than the three molars, which are hypsodont and 



1 Broom in a recent paper (1909) gives the dental formula for the milk and permanent 



? 3.4.5.6. 1.2.3. 



1 .-.- f 1. T 1-2-3 „ 1 r. 1-2.3 4.5.6. ,, 

 dentitions as follows: I. ., ^ „ ; C. -; P. :r"rr^-.-j-x ; M. 



L.Z.O 1 l..i..5.4.0.0. 



2.3.4..5.6. 1.2.3 



