CHONDEOCEANIUM 



311 



0.1 



g.r 



111 



.FiG. 155. Illustrating the development of the chondrocrauium in Lung-fishes. 

 (After Agar, 1906.) 



A, Protopterus, stage 31 ; B, Lepidosiren, stage 34 ; C, Lepidosiren, stage 38. cue, auditory capsule ; 

 g.r, floor of Gassorian recess; Ily, liyoid arch; i.o, intcropercular ; me, mcst'thnioid ; 3f, mandibular 

 arch; N, notochord ; o, opercular; oc.a, occipital arch; oc.r, occipital rib; o.p, occipital plate; o.t, 

 orbito-toini)cial ; /<.</. jit'ctoral girdle; P.O. position of Pinkus's organ ; p.q, palatoquadrate ; Q, quad- 

 rate ; s.n.c, suVmasal cart ilago ; I, tii-st branchial arch ; III, foramen for Oculomotor ; V, VII, foramina 

 fur Tri.ueminal and Facial. 



