458 PEOFESSOE J. AJSTDEESON ON THE 



this foramen and the three previously mentioned foramina, and at a considerably higher 

 level than it, there is a well-marked foramen below and slightly anterior to the post- 

 orbital process. It is directed upwards and rather backwards, apparently leading into the 

 frontal sinuses ; at least a fine wire inserted along it does not appear in the cranial cavity. 

 The spheno-palatine canal is of moderate size, and opens at a short distance anterior to 

 the sphenoidal fissure, and rather on a line external to it. Its lower border is formed 

 by the pterygoid plate of the palatine. The posterior palatine canal is very short, and 

 opens anterior to the external angle of the slightly thickened posterior margin of the 

 palate. The anterior palatine foramina are bounded in front, within, and externally by 

 the prsemaxillse, and posteriorly by the maxillse. The lachrymal foramen, which opens into 

 the orbit above and rather external to the infraorbital foramen, is marked at its anterior 

 border by a strong process that projects outwards and slightly backwards, being con- 

 tinued upwards along the margin of the orbit to near the postorbital process as a 

 distinct ridge as in Erinaceus ; and, as in that genus, the prelachrymal process itself is 

 perforated by a minute foramen. Externally the lachrymal canal appears as a distinct 

 ridge, arching forwards and downwards to the upper margin of the external orifice of 

 the infraorbital foramen. Immediately above the infraorbital foramen there is a small 

 deep lachrymal pit, which also occurs in a less-marked degree in Erinaceus, but is not 

 observed in Tujpaia. The infraorbital foramen is separated from this pit by a thin plate 

 of bone. It is a large opening leading into a wide and moderately long canal, that 

 opens by a large orifice immediately above the interior fang of the fourth premolar. 



To return to the base of the skull (fig. 2), the mesopterygoid fossa terminates in a 

 true excavation, but not of the same marked character as in Erinaceus. In Ilylomys the 

 tympanic bullae are more posteriorly divergent than in Erinaceus, and in this they more 

 approach Tupaia ; but the area between them is excavated into two shallow, elongated, 

 oval troughs lying side by side at the extremity of the basisphenoid, but separated from 

 each other by a well-marked, low, sharp, longitudinal ridge, and defined on the sides by 

 the expansions of the basisphenoid, which go to assist in the formation of the tympanic 

 bullae. At the base of these processes there are one or two small foramina. The 

 glenoid surface is nearly flat externally, but slightly concave internally. The condyles 

 of the occipital are divided, or nearly so, into two articular facets, of which the lower 

 is almost circular ; but the skulls do not appear to be young. There is a rather large 

 precondyloid foramen on each side, immediately below the condylar constriction ; and 

 anterior to it is a jugular foramen. There is a well-marked paroccipital process, 

 anterior to which are two rather obscure processes in the mastoid region, and behind 

 the glenoid surface a postglenoid foramen, but no process. The tympanic is ring-like ; 

 but there is a vacuity between it and the tympanic process of the basisphenoid, and its 

 anterior extremity is anchylosed to the process of the alisphenoid immediately below 

 the foramen ovale, which is enclosed by the last-mentioned bone. 



The mandible is proportionally shorter than that of Tupaia, and in general form it 



