Shufeldt: Osteology of Lasiopyga and Callithrix. 69 



neural arch is perforated. " The vertebral canal passes through all 

 the cervical vertebrae increasing in calibre as it approaches the thorax, 

 save in the last vertebra. In both Lasiopyga and Callithrix the 

 infeiior lamellae of the transverse processes are broadened from side 

 to side, and their extremities expanded, thus forming lengthened, 

 longitudinal processes. These inferior lamellae are absent in the 

 seventh cervical vertebra. The neural spine in the axis is thick and 

 relatively large; is much smaller in the third cervical, becomes sharp 

 and pointed in the fourth, after which it gradually becomes sharper 

 and longer to and including the seventh or last cervical. 



The seventh cervical in both Lasiopyga and Callithrix has a demi- 

 facet on either side of the centrum to form part of the articulation of 

 the first pair of ribs. 



In Lasiopyga, and especially in L. callitrichus, the neural spines 

 of the dorsal vertebrae are long, rather pointed, but with slightly 

 expanded apices. They become progressively and gradually shorter 

 as we proceed backward, and less and less inclined in that direction 

 (Plate XVIII, fig. 2i). The last two thoracic vertebrae have char- 

 acters approaching those of the anterior lumbars. In the last dorsal 

 vertebra the transverse processes are aborted, a gradual diminution 

 from the strong ones in the fore part of the series having taken place 

 and they are supplanted by the sharp-pointed pleurapophyses, directed 

 backwards, so that on the last dorsal we have a pair of these, as well 

 as a pair of ribs, which articulate only with the centrum of that 

 vertebra. These spine-like pleurapophyses persist in the lumbar 

 vertebrae, including the penultimate, becoming smaller and smaller, 

 and disappearing entirely on the last lumbar. In articulation they 

 powerfully assist in holding the prezygapophyses in place, being in 

 any instance situated just below a postzygapophysis, thus forming a 

 recess into which the prezygapophysis of the vertebra next following 

 accurately fits. Transverse processes commence again on the first 

 lumbar, and become more and more prominent to and including the 

 last one of this series (PI. XIX, fig. 22). 



The neural spines of the lumbal s aie conspicuously developed, 

 rather high, elongate, oblong, and are in each of these yertebrae nearly 

 as long as its centrum. Essentially all of these characters are repeated 

 in the spinal column of the marmoset; but in it the neural spines of 

 the last dorsals are not as long or as pointed. These monkeys have 

 long, slender ribs, requiring no special description. Barring the last 



