MUSEUM OF COMPARATIVE ZOOLOGY. 309 



oti. Chymiferous tube passing to the otocyst. 

 P. p. Proboscis. 



p b. Mass of pigment. 



p s. Pigment spots. 

 R. r. Outer pit (Riechgriibschen). 



r t. Tentacular base. 

 S. s. Stomach. 



sp. " Spurs " (small filaments or tentacles). 



st. Somatocyst. 

 T. t. Tentacle. 



Z". Small intermediate tentacles. 



tf. Tentacular appendages. 



t m. Basal portion of the tentacle into which it is absorbed. 



t e. Distal enlargement of the tentacle. 



1 1. Tentacular tubes. 

 U. u. Basal portion of proboscis. 



um. Gelatinous part of the lower floor (color pink). 

 V. v. Pigment in median portion. 



ve. Velum. 

 W. w. Constriction which separates median and distal portions. 



wm. Long cells (.'). 

 X. x. Pigment dots near constriction. 

 Y. y. Scattered pigment. 

 Z. 2. Half-absorbed tentacular appendage. 



FIGURES. 



1-9. Larval stages illustrative of the development of the chymiferous tubes of 

 Mnemiopsis Lcidyi, A. Ag. 

 1. Youngest larva just escaped from the shell (egg sac). The view is taken 



in a plane passing through the tentacles and the otocyst. 

 1 a. A larval Mnemiopsis seen from the aetinal pole. 

 2-4. Stages in growth illustrating the elongation of the chymiferous \ 

 vious to their union. 



5. Young Mnemiopsia in which the lobular tubes (If) have united. 



6. The same, still ohler than the last. 



6 a. View of tig. 6 in a plane at right angles. 



7. A stage more advanced than the last, in which the auricles have began to 



form. 



7 a. View of fig. 7 at right angles to the plane of the last. 



8. A larva in which the lateral and auricular tubes have united. 



9. Young Mnemiopsis with well-developed auricles and oral lobes. 

 !» a. Base of the tentacle of young Mhemia 



lti-1 I. Larval stages of Epenthesis folleata, &fc< V. 



10. Side view of tlie young, with six tentacles ami beginnings of a mv 



11. The same (oral view). 



12. Young E. folleata with eight tentacles (oral view V 



