MUSEUM OF COMPARATIVE ZOOLOGY. 173 



otocyst of Cyanea, Piute VII. fig. 12, c. The lateral tubes which enter their 

 bases are strictly homologous to the early conditions of the lateral branches in 

 the ephyra of Cyanea, Figs. 9, 10. That there is this resemblance between the 

 marginal sense bodies of the young Cyanea and the adult Aurelia is still another 

 fact added to many others, that Cyanea stands higher in the scale of life than 

 Aurelia, or that Aurelia is an arrested stage of development similar to the 

 young of Cyanea. 



Dactylometra quinquecirra, A. Ac. 



Plate VIII. Fig. 14. 



D. quinquecirra is a rare medusa in Narragansett Bay. One or two specimens 

 are taken each summer. The adult, one half natural size, is shown in Plate 

 VIII. fig. 14. The genus is characterized by the presence of five tentacles 

 between each pair of otocysts. In other respects it resembles Pelacjia, to which 

 genus it was referred by Desor. 



The umbrella is thickly pigmented with brown and red spots, which are 

 very large in the middle of the upper surface of the umbrella. The color of 

 the bell is pale blue and brown. The same color with pigmentation is likewise 

 found on the tentacles. 



There are oral appendages of two kinds, four of which are quite long, float- 

 ing gracefully along after the medusa as it swims in the water. The remaining 

 oral appendages are shorter, more ruffled, confined to the immediate vicinity of 

 the mouth, and extending only a short distance outside of the bell below the 

 lower floor. The stomach lobes are united at their bases, yet not by a solid 

 circular ring such as exists in Cyanea. Ovaries yellow, hanging in baglike 

 masses between the pillars by which the oral appendages are suspended. In 

 alcoholic specimens there are no circular muscular folds such as exist on the 

 lower floor of Cyanea. The whole umbrella is very flexible. Size six to ten 

 inches in diameter. There are generally five tentacles between each pair of 

 marginal sense bulbs. These tentacles vary in size, and oftentimes there are but 

 three or four between each pair of otocysts. The chymiferous tubes resemble 

 closely those of the genus Pelagia. They are not dendritic at their distal ends, 

 as is the case with Cyanea, nor branched as in Aurelia, but pass directly to the 

 vicinity of the otocysts, where they divide, sending a branch into the cavity 

 of this structure, and lateral forks which are continued into a tube which runs 

 along the margin of the disk. 



CTENOPHORA. 



Mnemiopsis Leidyi, A. Ao. 



M. Leidyi is one of the most common Ctenophores in Narragansett Bay. In 

 the latter part of the summer and early autumn these jelly-fishes fill the Avater 

 in Laboratory Cove, Newport, and can be found in almost all stages of develop- 



