138 G. E. Dobson — Osteology of Tricenops per sicus. [No. 2, 



of the basi-sphenoid with the pre-sphenoid. The cribriform plate is perfor- 

 ated by two large triangular foramina separated by a narrow bony process. 



The pterygoid plates are greatly expanded, forming broad, acutely 

 pointed, triangular projections directed downwards and slightly outwards, 

 giving width to the meso-pterygoid fossa which cpiickly narrows as it pro- 

 ceeds backwards, exposing the wide sphenoidal fissures. Posteriorly its roof 

 becomes continuous with the under surface of the basis cranii, as in Phyl- 

 lorhina, its sides curve outwards, forming the posterior boundaries of the 

 sphenoidal fissures which extend backwards as far as a fine drawn between 

 the glenoid fossse. There is no distinct foramen rotundum. 



In Phyllorhina the sphenoidal fissures are much narrower and shorter, 

 terminating posteriorly at some distance in front of a fine joining the 

 glenoid fossae. They are concealed in their whole extent by the lateral walls 

 of the meso-pterygoid fossa. The foramen rotundum is represented by a 

 small aperture in front of, and internal to the foramen ovale which occupies 

 the same position, relatively, as in Tricenops. The post-glenoid foramen 

 is small or absent. The meso-pterygoid fossa maintains the same width from 

 before backwards, or is slightly expanded posteriorly. About the middle its 

 lateral walls develop small, acutely pointed, hamular processes, curved back- 

 wards. 



In PJiinolophus the basi-occipital is extremely narrow between the audi- 

 tory bullae ; the foramen rotundum is united, as in Tricenops, with the 

 sphenoidal fissure which extends as far backwards as in the latter genus ; the 

 meso-pterygoid fossa is relatively wider anteriorly than in either Phyllorhina 

 or Tricenops, and conceals the narrow sphenoidal fissures to within a short 

 distance of its termination where its sides suddenly narrow, disclosing the 

 sphenoidal fissures posteriorly, and slightly further backwards curving out- 

 wards limit their posterior extent ; its roof is traversed by a narrow groove 

 terminating posteriorly in an excavation, thus differing from both Phyllor- 

 hina and Tricenops. 



The bony palate extends as far back as the middle of the last molar 

 tooth ; in Phyllorhina, it is limited by the posterior margin of the second 

 molar. 



The coronoid process of the mandible is very small, and in vertical 

 height less than the canine tooth, thus resembling Bhinolophiis more than 

 Phyllorhina ; the upper margin of the articular surface is level with the 

 summits of the molar teeth, and the ramus is pierced immediately beneath 

 and in front of the condyle by a large circular foramen directed upwards, 

 and slightly outwards.* 



* This infra-condyloid foramen of the mandible is probably unique in Tricenops, 

 in no other genus of Rliinolophidce have I found it, nor, so far as I can ascertain has 

 such a foramen been discovered in any other species of Chiroptera. 



