138 
G. E. Dobson — Osteology of Trioenops pensions. 
[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 quickly 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 line drawn between 
the glenoid fossae. 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 line joining the 
glenoid fossa;. 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 Truenops. 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 Rhinolophus the basi-occipital is extremely narrow between the audi- 
tory bull® ; the foramen rotundum is united, as in Triwnops , 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 Truenops, 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 Truenops, 
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 Bhinoloplms 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 Triamops, 
in no other genus of Hhinolophidm have I found it, nor, so far as I can ascertain has 
such a foramen been discovered in any other species of Chiroptera, 
