SKELETON IN THE FLYING LEMURS. 159 



of them perforated upon either side, in the longitudinal direction, by the 

 foramen for the vertebral artery. In each the centrum, is mucb com- 

 pressed from above, downward, which results in giving the articular facet 

 at either end a transverse elliptical form, the concave one being behind, 

 the convex one in front. The prezygapophyses are quite individualized 

 and project directly forward beyond the centra and the neural arch. 

 Postzygapophyses practically agree with what has been described for the 

 axis. All these vei'tebraj have a broad, compressed appearance with 

 their flat ventral aspects quadrilateral in outline. Small and stumpy in 

 the third cervical, the transverse processes become gradually more con- 

 spicuous to include the seventh, or last cervical, where they are produced 

 both forward and backward from a broad common pedicle. 



Among the leading dorsal vertebra the centra are much compressed 

 as we found them in the cervicals, but they gradually become more 

 cylindrical in form to the close of the series. Eeniform in outline, the 

 articular facets at either end have their concave edges upward. 



Greatly reduced in size and caliber throughout the dorsal region, the 

 neural canal is slightly compressed from above, downward, in the first 

 few dorsals, finally to become cylindrical among the ultimate ones. This 

 continues to be the case through the lumbar vertebne, until we arrive 

 at the last lumbar, where the canal is very much compressed from above, 

 downward, and with this form passes through the sacrum and the first 

 four caudal vertebree. On the fourth caudal the spinal cord receives its 

 last and very scant osseous protection, passing through a delicate little 

 arch on the superior aspect of the bone, posteriorly. 



Among all the dorsal vertebrse the diapophyses, or transverse processes, 

 are short and thick, and in all cases project directly outward from their 

 bases. At their nether extremities we note the usual facets for the 

 tubercles of the ribs articulated with them at these points. The capitular 

 facets for the heads of the ribs are shared in each case throughout the 

 dorsal series by two vertebrae, by which is meant that one-half of the facet 

 (a demifacet) is on the centrum of one vertebra and the other half on the 

 side of the centrum of the vertebra next following it. Ko exception to 

 this rule has been met with in the three specimens examined. Zyga- 

 pophysial processes here present their usual mammalian characters, the 

 postzygapophyses only becoming differentiated as true processes in the 

 last few bones of this region. 



The intervertebral foramina for the entire spinal column are formed 

 about as they are throughout the mammalian series, including man. 

 They are large in the cervical region, very much smaller in the dorsal 

 section, and increase in size again in the lumbar where they are longitu- 

 dinally slit-like, aoad are found in each case between the centrum and the 

 long, backwardly directed, spiny anapophysis on either side, at the pos- 

 terior end of the vertebra (figure 7). 



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