MUSEUM OF COMPARATIVE ZOOLOGY. 261 



opening, which leads from the stomach into the chymiferous cavity ahove. 

 Their function is unknown.* 



The marginal sense hodies of Linerges are very characteristic. They are 

 eight in number, and are situated in incisions alternating with the tentacles on 

 the bell rim. Each otocyst is very prominent, and at first glance appear- to 

 be destitute of a " hood." This impression is, however, not a true one, for the 

 hood in Linerges assumes a curious and at first unrecognizable form. 



When the otocyst is looked at from above it resembles a spherical sac, in the 

 centre of which, through the transparent walls, a single otolith mounted on a 

 short peduncle can be seen. The transparent sac in which this single otolith 

 is contained is the homologue of the " hood " of other Discophora. If the sac 

 be viewed from below, it will be found to be not a closed capsule, but an open 

 one, or that the wall of the sac is wanting on the under surface. The hood 

 has thus in Linerges assumed a caplike form reaching outward so as to envel- 

 ope the otolith on the upper side, and to leave the lower unprotected. The 

 otolith is a single spherical body, and not a rhomboidal structure as in Cyanea 

 and many others. There is no prominent ocellus, f 



No representative of a " Sinnespolster," or of an outer " Riechgriibschen," 

 was seen. Oral sense curtains and lappets are also wanting. 



The ovaries hang from the inner bell walls and seem to be in free com- 

 munication with the stomach. They are four in number, and have a horse- 

 shoe shape. Each ovary is made up of two halves, united together in such 

 a way that the gland has the peculiar arched form shown in the plate. The 

 ovaries have a dark brown color. 



The ova (PL IV. fig. 7) are laid in small black clusters, composed of from 

 fifteen to twenty eggs, which are agglutinated together. A segmentation of the 

 ovum begins shortly after the egg is dropped, when it becomes more transparent 

 and separates from its union with others of the same cluster. 



The first change in the segmentation is the elongation of the ovum into an 

 ovoid shape, blunt at one pole and more tapering at the opposite. The tit — t 

 plane of segmentation divides the egg into two unequal segment spheres ; one 

 formed from the pointed, and the other from the blunt pole of the ovum. 



Shortly after this first cleavage of the egg into two unequal spheres, a second 

 plane divides the larger of the two into two other spheres which are also of 

 unequal size, and we have an egg in which three segmentulcc can be seen. All 

 of these parts now assume a pyriform shape, and new segment-spheres are con- 

 stricted from them in the same way that the two spheres were first formed from 

 the original ovum. At the end of the second day after ovulation the ovum was 

 in the condition shown in fig. 12. The segmentation takes place in the water, 



* These filaments may be homologous to the "sexual filaments" of Cyanea. They 

 resemble closely in position the early condition of these structures in the ephyra of 

 Cyanea. See Bull. Mus. Comp. Zool., VIII. 8, PL VII. figs. 8, 9. 10. 



t There are many scattered pigment-cells, which may be an ocellus, in the region 

 of the style where this structure is commonly found. 



