254 ALICE JOHNSON AND LILIAN SHELDON. 



21. Spencek, W. B. — "Some Notes on the Early Development of Rana 



temporaria," this Journal, supplement, 1885. 



22. WiJHE, T. W. VAN. — " Ueber die Mesodermsegmente u. d. Entwicklung 



der K erven des Selachierkopfes," 'Konigliche Akad. v. Wiss. zu 

 Amsterdam,' 1882. 



23. Dtjkham, H. E. — " Note on the Presence of a Neurenteric Canal in 



Rana," 'Quart. Journ. Micr. Sci.,' June, 1886. 



EXPLANATION OF PLATES XXIV, XXV, and 



XXVI, 



Illusti'ating Alice Johnson's and Lilian Sheldon's Paper 

 " On the Development of the Newt (Triton cristatus)." 



All the figures represent single sections. They were drawn with a Zeiss's 

 camera lucida and Zeiss's obj. A, oc. 2, except Figs. 1, 2, and 3, which were 

 drawn with obj. b, oc. 2 ; Figs. 6 and 7 with obj. c, oc. 2 ; and Figs. 4, 5 

 and 30 with obj. c c, oc. 2. Fig. 12 was drawn with obj. a, oc. 2, and after- 

 wards reduced by one half; and Figs. 13, 16, 17, 18, 36, 37 and 38 were 

 drawn with obj. a, oc. 2, and afterwards reduced by one third. 



N.B. — Grey denotes epiblast, and organs derived from it; brown denotes 

 mesoblast ; and yellow denotes hypoblast, and organs derived from it. 



Alphabetical List of Reference Letters. 

 Aud. Ear. Bl. Blastopore. Ch. Notochord. F. Aud. rt. Root of Facio- 

 auditory nerve. F. B. Fore-brain. F. G. Fore-gut. Gass. Gasserian gang- 

 lion. G. VII. Ganglion of 7th nerve. G. IX. Ganglion of 9th nerve. 

 H. B. Hind-brain. H. G. Hind-gut. Inf. Infundibulum. Lat. V. Thicken- 

 ing of nervous layer of epiblast to form sense organ corresponding to 5th nerve. 

 Lai. VII. Thickening of nervous layer of epiblast to form sense organ corre- 

 sponding to 7tli nerve. Lat. IX. Thickening of nervous layer of epiblast to 

 form sense organ corresponding to 9th nerve. M. B. Mid-brain. Mes. Meso- 

 blast. N. C. Neural ridge. Olf. Olfactory epithelium. 0. V. Optic vesicle. 

 P. a. g. Post-anal gut. Pit. Pituitary body. Sp. c. Spinal cord. St. Sto- 

 modeeum. Thai. Thalamencephalon. Thi/. Thyroid body. V. C. I. First 

 visceral cleft. V. C. II. Second visceral cleft. III. Third nerve. V. Fifth 

 nerve. VII. Seventh nerve. IX. Ninth nerve. /// rt. Root of 3rd nerve. 

 V rt. Root of 5th nerve. VII rt. Root of 7th nerve. VIII rt. Root of 

 8th nerve. IX rt. Root of 9th nerve. V d. Dorsal branch of 5th nerve. 

 VII d. Dorsal branch of 7th nerve. IX d. Dorsal branch of 9th nerve. 



