SKELETON IN THE FLYING LEMURS. 161 



vertebral characters of the bones in the fore part of the column. The 

 lateral processes, especially, are developed in the first four caudals, most 

 «o in the third and fourth, where they are extensive horizontal plates with 

 circular limiting borders. Zygapophysial processes are well developed in 

 the leading caudals, particularly the prezygapophyses, which subsequently, 

 as we pass down the skeleton of the tail, become a pair of rounded tubercles 

 situated side by side on the supero-anterior aspect of the bone. These 

 persist in a number of vertebra as we pass toward the end of the tail. 



On the ventral aspect of the skeleton of this part of the vertebral chain 

 in Steere's specimen, between the sixth and seventh and the seventh and 

 eighth vertebra, and situated directly over the intervertebral articulations, 

 we note a pair of minute ossicles, ellipsoidal in form, and placed side 

 by side, at an interval of about one millimeter. They are perfectly free 

 and are held in place by delicate ligaments. Possibly similar pairs may 

 be found posteriorly between a few more vertebrae, but after that they 

 surely disappear altogether. These last have evidently been lost in the 

 specimen, and it is fair to presume that these ossicles probably represent 

 rudimentary chevron bones. 



Flower,'^ under the Insectivora, makes no mention of the ribs and 

 sternum, although he lightly touches upon them for Talpa, Sorex, Erina- 

 ceiis, and Rhynchocyon. 



Viewed as a whole the osseus framework of the thorax in Cynocephalus 

 is quite in keeping with what we meet with in this part of the skeleton 

 in any average mammal, being decidedly more so than in Talpa, although 

 the mole and the colugo each possess 13 pairs of ribs. 



The chest capacity of Cynocephalus is considerable, notwithstanding 

 the fact that it is much contracted anteriorly, where it is bounded by the 

 first pair of ribs, the first dorsal vertebra, and the presternum. From 

 this region it gradually, though very uniformly, expands to the plane of 

 its posterior termination, where it has an average transverse diameter of 

 6 centimeters. 



Owing to the greater size. of the leading dorsal vertebrse and to the 

 small dimensions of the ribs themselves the first three pairs of ribs have, 

 upon either- side, greater intervals between them than any other members 

 of the series. These ribs are somewhat roundish in form, although 

 exhibiting a disposition to flatten at their vertebral ends as we pass 

 backward. In the fourth pair this flattening associated with an increased 

 width is pronounced, and from thence on is continued to include the 

 last pair. This accounts for the decrease in the width of the intercostal 

 spaces after passing the third pair of ribs, so that each intercostal space 

 is about equal to the ribs that bound it. There is very little difference 

 in the width of the ribs from the fifth to the thirteenth pair, inclusive, 



" Osteology of the Mammalia, 94-96. 



