DEVELOPMENT OF PEEIPATUS NOVAl-ZEALANDlAi. 293 
EXPLANATION OF PLATES XXY & XXVI, 
Illustrating Lilian Sheldon’s paper, “ On the Development of 
Peripatus novse-zealandiae.” 
List of Reference Letters. 
Bl. Blastoderm. Btp. Blastopore, c. Cavity, corresponding to polar area 
of P. capensis. Pm. A. Protoplasmic area. Pr. Gr. Primitive groove. 
Pr. St. Primitive streak. 
All the figures were drawn with Zeiss’s camera lucida ; Figs. 3 a and 9 were 
drawn under Zeiss’s oc. 2, obj. cc; Fig. 4 under Zeiss’s oc. 2, obj. a; and 
the rest under Zeiss’s oc. 2, obj. B. 
Fig. 1. — Transverse section through an ovum, in which the blastoderm has 
grown nearly half way round the yolk. 
Fig. 2. — Transverse section through the centre of an ovum, in which the 
yolk is nearly covered by the blastoderm. 
Fig. 3. — Transverse section through an ovum, in which the primitive streak 
is beginning to arise. 
Fig. 3 a. — Transverse section through the portion of the same ovum which 
is not covered by the blastoderm, drawn under a higher power. 
Fig. 4. — Transverse section through the centre of a young ovum before the 
formation of the blastoderm, showing the multiplication of the nuclei in one 
region near the periphery. 
Figs. 5, G, and 7 . — Three transverse sections through an ovum in which 
the blastopore is well formed. 
Fig. 5. Through the blastopore. 
Fig. G. Just behind the blastopore. 
Fig. 7. Near the posterior end of the primitive streak. 
Fig. 8. — Transverse section through an ovum with a primitive streak. 
Fig. 9. — Transverse section through a portion of the same ovum, to show 
the invagination at the blastopore beginning at the anterior end of the primi- 
tive streak. Brawn under a higher power than Fig. 8. 
Fig. 10. — Transverse section through an embryo with appendages, to show 
the duct of the first somite opeuing to the exterior. 
Fig. 11. — Transverse section through the same embryo four sections pos- 
terior to Fig. 10, to show the duct opening into the first somite. 
VOL. XXIX, PART 3. NEW SER. 
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