226 



REPTILIA. 



may be left a median space, closed by skin or cartilage (Triort </.<-, 

 Chelonia, etc.). The spinous processes and ribs of the thoracic vertebrae 

 take part in the formation of the large carapace, as well as a number 

 of paired and unpaired osseous dermal plates, which are placed partly 



FIG. 646. Skeleton of Cittudo (Emy*) < HI-'>IHHU. V, vertebral (neural) plates; C, ensta 

 plates ; M, marginal plates ; Nu, nuchal plate ; Py, pygal plate ; B, plastron (ventral 

 shield) ; Cl, clavicle ; Jcl, inter-clavicle ; Sc, scapula ; Co, coracoid ; Pco, acromial 

 process (pro-coracoid); PI, pubis ; ./, ischimn ; Jl, ilium; //, hurnerus ; E, radius; 

 U, ulna; Fe, femur; T, tibia; F, fibula. 



in the median line in the neck (nuchal plate), and in the sacral region 

 (pygal plate), and partly laterally at the edge of the shield (22 mar- 

 ginal plates). 



While the spinous processes of eight of the thoracic vertebra? (2nd 



