Observations on the development of the excretory system in Turtles. 



711 



Description of Plates. 



Plates 45—50. 



Abbreviations. 



a cells for walls of aorta 



a. b aortic branch 



ao aorta 



h basis 



hi blastema 



c. a caudal artery 



cd collecting duct 



ch chorda 



cil cilia 



coel coelom 



c. t closed tubule 



C. V cardinal vein 



d duct 



ect ectoderm 



ent entoderm 



f funnel 



gl glomus 



gli glomerulus 



h heart 



i intestine 



l.h lung buds 



mes mesonephros 



mes. h mesonephric basis 



mes.bl mesonephric blastema 



mes. t mesonephric tubules 



met.hl metanephric blastema 



met. t metanephric tubules 



my myotome 



n nerve 



n. c neural cord 



oes oesophagus 



0. t open tubule 



ov primitive ova 



ov.d blastema of oviduct 



ph pharynx 



pr. b pronephric basis 



j)r. t pronephric tubule 



som somite 



w. d Wolffian duct. 



Plate 45. 



Cross sections of Aromochelys embryo of stage II, showing the 

 pronephric welt {pr. b) extending from the 6th to lO'h somites. 



Fig. 1. Somite 6, section 



rig- 2. „ 6, „ 



Pig. 3. „ 6, „ 



rig. 4. „ 6, 



Fig. 5. „ 6, 



„ 9- 



„ 10 (between somites 6 and 7). Pro- 

 nephric welt continuous and position of mesonephric basis {mes. b) in 

 the middle plate is clearly seen on the right. 



Figs. 3 — 5 show cells (a) slipping from the sclerotome to form 

 the walls of the aortae. 



