THE DEVELOPMENT OF PERIPATUS CAPENSIS. 467 
PLATE XXXII. 
All the figures on this Plate are of embryos of Peripatus capensis. 
Pigs. 23 — 27. — Prom the original drawings by Miss Balfour, a. Denotes 
the anterior extremity. 
The remainder of the figures on this Plate from drawings by Mr. E. Wilson. 
Pig. 23. Stage between A and B. With three somites and elongated 
blastopore. Length of embryo ’7 mm., length of blastopore ’45 mm. 
Pig. 24. Stage between A and B. With five somites. The blastopore is 
closing in its middle portion. Length of embryo '74 mm., of blasto- 
pore '46 mm. 
Pig. 25. Stage B. The blastopore has completely closed in its middle 
portion and given rise to two openings, the embryonic mouth and anus. 
The anterior pair of somites have moved to the front end of the body, 
and the primitive groove is very marked. Length of embryo 1'32 mm. 
Fig. 26. Stage C. Embryo, in which the flexure of the hind end of the 
body has begun ; with about thirteen somites. The remains of the 
original blastopore are present as the mouth, placed between the second 
pair of mesoblastic somites, and the anus, placed on the concavity of 
the commencing tail flexure, and still removed from the hind end of 
the body. Greatest length when lying on its back 1’12 mm. 
Pig. 27. Side view of same embryo. 
Pigs. 28 and 29. — Stage D (spiral stage). 
Pig. 28. A young embryo of this stage, viewed from the side. With 
commencing antennae and dorsal projection (d). 
Pig. 29. Bather older embryo of same stage (end of spiral stage), side 
view. Eyes ( e ) as pits. Jaws and postoral appendages sprouting. 
Budiments of eleven pairs of legs. Length from anterior end of head 
to bend ( d ) P6 mm. At. Antennae, d. Dorsal thickening, e. Eye. 
j. Jaw. or. p. Oral papilla, p. s. Praeoral somite. 
Pigs. 30 — 34. — Stage E. 
Pig. 30. Side view of straightened-out embryo. Antennae ringed. Bucca 
fold (L) extending round the jaw (j) on to the ventral surface. Sixteen 
pairs of legs. Praeoral somite ventrally grooved. Apex of oral papilla 
perforated. Length from front end of praeoral lobe to bend ( d ) 1'76 mm. 
Eye still as an open pit (it is usually closed at this stage), d. Dorsal 
ectodermal thickening, e. Eye. F. 1 .... 8pc. Peet. j. Jaw. L. 
Lip. or. p. Oral papilla, p. s. Praeoral somite. 
Pig! 31. Embryo of same stage, in natural position in egg membrane. 
Pig. 32. Hind end of embryo of same stage, ventral view. a. Anus. 
s. 20. 20th somite, s. 19 and 18. Legs of 19th and 18th somites. 
