GANOCEPHALA 17 J 



to the arches and peripheral vertebral elements.* In this 

 structure the old carboniferous reptile resembled the existing 

 Lejridosiren, and affords further ground for regarding that 

 remarkable existing animal as one which obliterates the line 

 of demarcation between the fishes and the reptiles. 



Coincident with this non-ossified state of the basis of the 

 vertebral bodies of the trunk (fig. 65, c), is the absence of the 

 ossified occipital condyles which characterize the skull in 

 better developed Batrachia. The fore part of the notochord 

 has extended into the basi-sphenoid region, and its capsule 

 has connected it by ligament to the broad fiat ossifications of 

 expansions of the same capsule, forming the basi-occipital or 

 basi-sphenoid plate. In fig. 65 are represented the chief 

 modifications of the vertebra?, as shown in the neck, thorax, 

 abdomen, sacrum, and tail. The vertebrae of the trunk in the 

 fully-developed full-sized animal present the following stage 

 of ossification : — 



The neurapophyses (fig. 65, n) coalesce at top to form the 

 arch, from the summit of which was developed a compressed, 

 sub-quadrate, moderately high spine, with the truncate or 

 slightly convex summit expanded in the fore-and-aft direction 

 so as to touch the contiguous spines in the back ; the spines 

 are distinct in the tail. The sides of the base of the neural 

 arch are thickened and extended outwards into diapophyses, 

 having a convex articular surface for the attachment of the 

 rib, j)l ; the fore-part is slightly produced at each angle into a 

 zygapophysis looking upwards and a little forwards ; the 

 hinder part was much produced backwards, supporting two- 

 thirds of the neural spine, and each angle developed into a 

 zygapophysis, with a surface of opposite aspects to the anterior 

 one. In the capsule of the notochord three bony plates were 

 developed, one on the ventral surface, and one on each side, 



* Reptilien aus der Steinkohlen Formation in Deutchland, Sechster Band, 

 p. 61. 



