MUSEUM OF COMPARATIVE ZOOLOGY. 309 



oti. Ch3Tniferous tube passing to the otocyst. 

 P. p. Proboscis. 



p b. Mass of pigment. 



]) s. Pigment spots. 

 E. r. Outer pit (Piiechgriibsclien). 



r t. Tentacular base. 

 S. s. Stomach. 



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



St. Somatocyst. 

 T. ;;. Tentacle. 



<*. Small intermediate tentacles. 



tf. Tentacular appendages. 



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



t c. Distal enlargement of the tentacle. 



1 1. Tentacular tubes. 

 U. u. Basal portion of proboscis. 



u m. 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. 



win. Long cells (/). 

 X. X. Pigment dots near constriction. 

 Y. y. Scattered pigment. 

 Z. z. Half-absorbed tentacular appendage. 



FIGURES. 



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

 Mncmiopsis 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 fl. A larval Mncmiopsis seen fi'om the actinal pole. 

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

 vious to their union. 



5. Young Mnemioimis in which the lobular tubes [It) have united. 



6. The same, still older than the last. 



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



7. A stage more advanced than the last, in which the auricles have begun 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 Mncmiopsis with well-developed auricles and oral lobes. 

 9 a. Base of the tentacle of young Mncmiopsis. 



10-14. Larval stages of £)jcn</icsfs/o?^c«to, McCr. 



10. Side view of the young, with six tentacles and beginnings of a seventh. 



11. The same (oral view). 



12. Young E. foUeata with eight tentacles (oral view). 



