88 THE MEDUSAE. 



in diameter, has seven (PI. 16, fig. 3). Of the Hawaiian specimens, several 

 have twelve, thirteen, and fourteen each, and one sixteen. The tentacles, of 

 the usual structure, are about as long as the diameter of the bell, stiff, and 

 in life carried recurved into the bell cavity. There are no such nematocyst 

 pads at their bases as Haeckel ('81) has figured for P. pantheon. 



In the largest specimen there are from eighteen to twenty otocysts per 

 lappet (PI. 45, fig. 1), the same number that Haeckel records. Mayer (: 06) 

 observed only three per lappet; but I find that his large Hawaiian speci- 

 mens also have about eighteen to twenty. In the smallest specimen there 

 are only four or five per lappet (PI. 16, fig. 3). In a slightly larger one, 

 5 mm. in diameter, five was the largest number counted in any lappet ; but 

 in a specimen 11 mm. in diameter there are from seven to nine per lappet. 



The octocysts themselves are of the usual type, containing two or three 

 otoliths and situated on ectodermic pads (PI. 20, fig. 3). The otoporpae 

 vary in length, the lateral ones, reaching to about the level of the bases of 

 the tentacles, being longest ; they anastomose somewhat ; those of one lappet 

 are shown in PI. 45, fig. 1. They are not bounded by definite caps of ectoderm 

 cells, as is the case in P. maiiagon (p. 86), but grow narrower and narrower, 

 until finally they become indistinguishable. They seem to have been over- 

 looked entirely by Mayer. 



Gastro-vasciilar system. — The mouth in all the specimens is widely 

 opened ; there is no trace of proboscis. The canal system is well devel- 

 oped and unusually prominent. In a small specimen 5 mm. in diameter the 

 endoderm layer is thickened along the proximal face of the ring canal 

 (PI. 20, fig. 1), forming a ridge, variously folded, running lengthwise of the 

 canal. In the adult specimen there is no trace of this structure, the endo- 

 dermic lining of the canal being of uniform thickness throughout. 



Gonads. — These, in all the large specimens, are definitely three-lobed ; 

 each consisting of a central and two lateral lobes (PI. 20, fig. 2). In the 

 largest specimen the central lobe is rounded and supported by a prominent 

 gelatinous eminence (PI. 45, fig. 2, g. pr.), while the lateral lobes, which are 

 the chief sexual portions of the gonads, are flat, leaf-like, and variously 

 subdivided. There is considerable variation in the conformation of these 

 organs in large specimens, though all agree in having them definitely 

 three-lobed. In the largest Hawaiian specimen, which is in a rather more 

 advanced state, the three lobes are of about equal size, sausage-shaped, 

 the lateral ones being only wavy in outline, not definitely subdivided, while 



