242 BULLETIN OF THE 



These may be properly termed anterior and posterior tympanic vacu- 

 ities, or foramina, corresponding to the foramen lacerum medium and 

 foramen lacerum poster ius basis cranii of anatomists. Plate II. Figs. 9, 

 10, a. 



2. " Orbito-nasal " includes the vertical plate of the palatine, and 

 the margins of the palatine, maxilla, alisphenoid, orbitosphenoid, and 

 frontal, at their lines of juncture, as also the combination of certain 

 foramina. Plate II. Fig. 7, a, b. 



3. " Palatine " designates the anterior and posterior portions of the 

 palate, one or both. Plate I. Figs. 1, 2, a, b. 



4. " Facial " includes the side wall of the face, the latero-nasal por- 

 tions of the maxilla, and the anterior root of the zygoma. Plate II. 

 Fig. 8, a. Plate I. Figs. 3, 5, a, b. 



5. The " Occipito-squamosal " is the space comprehended between the 

 supraoccipital, exoccipital, and squamosal. Plate II. Fig. 11. 



6. The " Squamosal " and " Parasquamosal " are indicated by the 

 terms used. Plate I. Fig. 4, b. 



Ihe cranial vacuities in the various orders of the Mammalia occur 

 as follows. 



MoNOTREMATA. — The skull of the Echidna presents no vacuities. In 

 the Ornithorynchus, there are relatively large anterior and posterior 

 deficiencies, the first representing the foramen ovale, and the second 

 the jugular and the prsecondyloid foramina combined. There are also 

 small ones in the basisphenoid. 



Marsupialia. — Many of the Macropodidse have large posterior palatine 

 vacuities. These are present also in Phascolarctos (Plate I. Fig. I, a), 

 in the Dasyu^'dag (Plate I. Fig. 2, a, b), and in the Peramelidae. Pera- 

 meles lagotis has a large oval vacuity which extends from the second pre- 

 molar to the penult molar, and posterior to this are found several small 

 ones. In the Didelphidae there are large posterior palatine vacuities. 



Edentata. — This order is singularly free from cranial deficiencies. 

 In the Dasypodidse the posterior tympanic vacuity, or foramen lacerum 

 posterius, is somewhat enlarged. Among the Sloths, Cholo?ptis hoffmanni 

 presents considerable deficiencies in the basi-sphenoidal region. 



Chiroptera. — In a few genera, notably in Pteropus, the posterior 

 tympanic vacuities are large. 



Insectivora. — In some of the Erinaceidae, the post-tympanic are 

 large, while there are also extensive post-palatine vacuities, especially in 

 Erinaceus europceus. In Sorex, large latero-basal ones are found, and 

 Tupaia has a large longitudinal 'central deficiency of the malar, in addition 

 to the palatal vacuities. 



