BY WILLIAM A. HASWELL, M.A., D.SC. 597 



XXXI. — Spoof, A. R. Beitrage zur Embryologie u. vergleichenden Ana- 

 tomieder Kloake.u. Urogenitalorgane bei den hoheren Wirbel- 

 thieren. [Abstract in Zool. Jahresber., 1883, IV., p. 140]. 



XXXII. — Whitman, C. 0. On a rare form of the Blastoderm of the 

 Chick. Quart. Journ. Micro. Sci. Vol. XXIII. 



XXXIII. — WiJHE, A. VAN. Ueber den vorderen Neuroporus und die 

 Phylogenetischen Function des Canalis neurentericus der 

 Wirbelthiere. Zool. Anzeiger VII. 



XXXIV. — Wolff, W. Ueber die Keimblatter des Huhnes. Archivf. mikr. 

 Anat. XXI. (1882). 



EXPLANATION OF PLATES. 

 Plate viii. 



Fig. 1. — Blastoderm of emu after 70 hours' incubation, with well-advanced 

 primitive streak and primitive groov 3 f'^w'.^ on a narrow posterior 

 prolongation (p.) of the area pellucida (ap.) The letter h. 

 points to the slightly convex anterior border of the mesoblast 

 extending forwards towards the region of the future head of the 

 embryo, ao. area opaca. From fresh specimen. 



Fig. 2. — Blastoderm of 66 hours ; rather further advanced than the pre- 

 ceding ; the posterior prolongation of the area pellucida no 

 longer sharply marked off from the rest, a crescentic groove (h.) 

 marking the anterior limit of the mesoblast and of the medullary 

 ]Aa.tQ (m.p.), 2:»;-. primitive streak and groove. From prepared 

 specimen. 



Plate IX. 



Fig. 3. — Blastoderm of 78 hours, with advanced head-fold f'/f.^ and rudi- 

 mentary medullary groove and medullary folds (m.). From 

 fresh specimen. 



Fig. 4. —Blastoderm incubated for 69 hours, considerably further advanced 

 than that represented in fig. 3, with well-marked head (h.) and 

 five pairs of protovertebras. The medullary folds have become 

 prominent and have almost met in the middle region of the head : 

 the primitive groove is still of considerable extent, h.a. head- 

 fold of amnion. Sp. splanchnopleure. From prepared specimen. 



