174 



REPTILIA 



CLASS III 



foramen. The orbits are oval, relatively small, and placed slightly in front of the 

 middle ; not far removed from them are the external nares. The impaired frontal is 

 much elongated, the premaxillae only moderately so, and the prefrontals are small and 

 triangular. The long and narrow maxillae unite posteriorly with a slender jugal, 



Fig 276. 



Nofhosauru* mirabilis, Miinst. Muschelkalk; Bayreuth, Germany. A, The five anterior cervicals. 



B, Two dorsals. C, Three caudal vertebrae, i/ 2 (after von Meyer). 



which enters into the temporal arcade. Pterygoids and palatines are strongly 

 developed ; the internal nares are placed far forwards, on either side of the paired 

 vomer. A single series of conical, slightly curved, and striated teeth (Fig. 272) is 



borne by the maxillae, pre- 

 maxillae, and dentary. All of 

 the rostral and one or two of 

 the anterior maxillary teeth are 

 considerably enlarged. 



Owing to the sutural union 

 between the vertebral centra and 

 their neural arches, the former 

 are usually found detached in 

 the fossil state, and exhibit a 

 cruciform impression on the 

 dorsal surface (Fig. 2 75). There 

 are about twenty cervicals (Fig. 

 276), all of which excepting atlas 

 and axis bear short, curved, 

 double-headed ribs. The ribs of 

 the trunk region are stout, single- 

 headed, and attached to the trans- 

 verse processes of the neural 

 arches. In this region tin- 

 neural spines are more strongly 

 developed, and the zygapophyses 

 more weakly, than elsewhere in 

 the vertebral column. The caudal vertebrae have single-headed ribs attached to their 

 centra, and also small chevron bones. The abdominal ribs comprise a median longi- 

 tudinal series sharply bent in the middle line, and a paired lateral series. 



In the pectoral arch (Fig. 277) the clavicles are well developed, and form a regular 

 arch into which a small, oval interclavicle enters. The ends of the clavicular arch are 



Fig. 277. 



Notlwsaurus mirabilis, Miinst. Muschelkalk; Bayreuth, Ger- 

 many. Dorsal aspect of pectoral arch, l/ 5 . cl, Clavicle ; qot, Cora- 

 coid ; id, Interclavicle ; sc, Scapula. 



