THK DKVKLOi'MENT OF APLYSIA PUNCTATA. 539 



EXPLANATION OF PLATE 22 



) 



Illustrating Mr. A. M. Carr Sauuders and Miss Margaret 

 Poolers paper on "The Development of Aplysia 

 punctata." 



Explanation of Abbreviations in Fiuures. 



A. Anus. A.c. Anal cells. C. Coelom. C.c. Cerebral commissure. 

 C.d.e. Dorsal extension of ccelom. C.(j. Cerebral ganglion. C.v.e.l. 

 Ventral extension of coelom on left side. C. v. e. r. Ventral extension of 

 cojlom on right side. F. Foot. Int. Intestine. K. 1. Primitive kidney. 

 K.2. Secondary kidney. L.l Left liver. 31. Mouth. M.c. Mantle 

 cavity. Ms. Mesoderm. (Us. (Esophagus. 0. Otolith. Ot. Otocysts. 

 P. (J. Pedal ganglion. R.I. Right liver. Sh.yhl. Shell-gland. St. 

 Stomach. V. Velum. 



N.B. — This explanation of lettering api^lies to Text-figs. 15 to 20 

 (pp. 536-538), as well as to the figures on PI. '2'2. 



Fig. 1. — Embryo at the stage immediately before the beginning of 

 rotation, seen from the right side. 



Fig. 2. — Same embryo seen in diagrammatic optical section ; the 

 ectoderm is represented as peeled ofi:' from the right half of the embryo 

 and thus seen in section. 



Fig. 3. — Slightly older embryo represented as in tig. 2. 



Fig. 4. — Slightly diagrammatic view of an embryo about twenty-four 

 hours older than that shown in fig. 3, seen from the right side. 



Fig. 5. — Similar view of older embryo, showing first appearance of the 

 ccelom (coloured red). 



Fig. 6. — Similar view of still later stage. The embryo has now 

 assumed its characteristic veliger form. 



Fig. 7. — Similar view of an embryo a few hours before its emergence 

 fx'om the capsule. 



Fig 8. — Similar view of a free-swimming larva. 



Fig. 9. — Free-swimming larva seen from the dorsal surface. 



