114 DISCOPHOR^. • Part III. 



as shown in Fig. 4, while the surface, again, is covered with cells varying in size 

 and arrangement, and assuming different appearances in the various states of con- 

 traction of the tentacles themselves. Where the lasso-cells are scattered uniformly 

 over the whole surface, as in Fig. 9, the tentacles appear more even, but where 

 they are grouped in clusters, as in Figs. 7, 8, and 10, their surfiice is already more 

 uneven, and in a state of contraction these clusters are more or less raised, like 

 tubercles, as in Fig. 8, and at times many project like warts attached to an other- 

 wise smooth surface {Fig. 5). This appearance, however, is presented only in a 

 state of utmost contraction of the tentacles, Avhen the more elongated epithelial 

 cells, which define the areas occupied by clusters of lasso-cells, as seen in Fig. 6, 

 are contracted in the form of prominent ridges, as in Fig. 5. 



It has already been stated, Avhen describing the young Cyanea versicolor, that 

 the surface of its disk is covered with hollow papillae; but what becomes of these 

 in course of time, has not been ascertained. The outer surface of the lobes of 

 the actinostome is also covered with similar, but very minute papillae, in the young ; 

 but nothing of the kind has been noticed in the adult. 



SECTION VI, 



CYANEID^E AS A FAMILY. 



The form of the Cyaneidoe is so characteristic, that there is no difficulty in 

 distinguishing it from that of other Discophora?. The sudden reduction of the 

 thickness of the gelatinous disk towards its margin, in connection with the width 

 of the radiating pouches, which extend from the main cavity to the margin of 

 that disk, and the manner in which the narrow pouches terminate in small lobes, 

 while the broad pouches, alternating with them, terminate in broad lobes, combined 

 with the ramifications of these pouches into branching sacs, extending to the very 

 margin of the lobe, give these Medusae an appearance quite peculiar. The position 

 of the eyes at a considerable distance from the margin, and the circumstance that 

 the tentacles hang from the lower side of the disk, at a still greater distance 

 from the disk, contributes further to distinguish this fiimily from all other Mediisfe. 

 If to these characters we add the prominent concentric and radiating folds of 

 the lower floor, the large, pendant genital pouches, and the extraordinary devel- 

 opment of the actinostome, we have a combination of characters not found in 

 any other Discophorae, and which justly entitle these Acalephs to be considered as 

 a distinct family. They differ from the Aurelidae, not only by the presence of their 



