404 TPIE OSTEOLOGY OF VULPES MACROTIS. 



On the external surface of either ramus in front there are to be seen two more 

 foramina, — the anterior one is the mental foramen, and is at a point below the 

 diastema between the first and second premolars ; the other, behind it, smaller in 

 size, is slightly in front of the corresponding interval between the second and third 

 premolars. In C. latrans they are nearly of a size, and the posterior one is im- 

 mediately below the centre of the third premolar. In all instances these foramina 

 are in the same horizontal plane and midway between the alveolar and lower border 

 of the ramus. Viewing the ascending portion of either ramus from behind, it will 

 be seen that it curves gently outward, which is the case in all of the Canidae. 



Professor Huxley made some interesting comparisons of this aspect of the 

 mandible among groups more or less remotely or nearly allied to the canine group. 6 



The Axial Skeleton. 



Vulpes macrotis may be said to have a somewhat delicate frame constituting 

 the skeleton of its trunk. The cervical, dorsal and lumbar vertebrae all possess 

 thin, sharpened and produced processes, thus doing away with all appearance of 

 heaviness in structure or bulkiness in form, as we notice in some small mammals. 

 The caudal vertebrae again are slender and elongated, making the skeleton of the 

 tail appear lash-like and frail. Much lateral compression characterizes the skeleton 

 of the thorax, the ribs being long and not at all stout, while the sternum has a 

 corresponding structure, the segments composing it being small, elongated, and 

 more or less slender. For the size of the animal, the pelvis is rather a stout bone, 

 but at the same time by no means strikingly so. In the number of vertebra 

 possessed by Vulpes macrotis^ or in the specimen now being examined by me, it 

 agrees exactly with a specimen examined by Sir Wm. Henry Flower of Cam's 

 vulpes ; in other words, it has seven cervicals, thirteen dorsals, seven lumbar, three 

 sacrals, and twenty-one caudal vertebras. Professor Flower met with a specimen of 

 Cam's lagopus that had the same number in the various divisions of the vertebral 

 chain, while in another case of Cams vulpes the animal had but nineteen caudal 

 vertebrae. All of the ferine forms of the Canidae, so far as we know, possess seven 

 cervicals and three sacrals. Variation sometimes takes place in the domesticated 

 breeds of dogs in the lumbar and sacral regions, as Flower found a German boar- 

 hound with fourteen thoracic or dorsal vertebrae ; Newfoundlands and mastiffs with 

 eight lumbar vertebrae ; and a greyhound with four sacrals. Cam's procynoides has 

 fourteen thoracic and but six lumbar vertebrae, and C vulpes has been known to 

 have the same number. Otocyon megalotis has the usual number in the series, but 

 has twenty-two vertebrae in the skeleton of its tail. It is this caudal part of the 

 vertebral column that varies most in this particular. Omitting the domesticated 

 breeds of clogs, however, it probably can be said with truth for the Canidae that the 

 number of caudal vertebrae are never less than fourteen (Icticyon venaticus) nor 

 more than twenty-two, which is the case, as has just been noted, in Otocyon 

 megalotis. 



6 P. Z. S., 1880, p. 263, fig. 14. 



