652 MEDUSA OF THE WORLD. 



As a matter of fact the mouth-arms of all known species o{ Cc plica give rise to secondary 

 dichotomous, or dendritic, branches, and all are laterally compressed. Moreover, we can not 

 separate genera merelv upon the relative size of the mouth-arm-filaments, for confusion is 

 certain to result. 



" Microstylus" of Kishinouve is evidently a Cephea closely allied to C. t\phlodcndrium. 



I have therefore broadened the definition of the genus Cephea to include all Rhizostomata 

 dichotoma with a wart-bearing central area upon the exumbrella and with 8 forked mouth- 

 arms, the forms of which are themselves still further branched. 



In the collection of Cepheas made b}' the U. S. Fish Commission steamer Albatross in 1908, 

 I find an intergrading series among specimens of Cephea collected all at the same time on 

 the surface at Jolo, Philippine Islands. In some there is no central dome, the exumbrella 

 being quite flat, and in others there is a low but well defined dome. In some the exumbrella 

 warts are large and mammiform, while in others thev are mere granules, often absent over 

 wide areas or leaving the center smooth. The filaments upon the mouth-arms and arm-disk 

 may be absent or long and filiform. Thus among these intergrading individuals (evidently 

 all of one and the same species) some are identical with Forskal's "Medusa octostyla," others 

 are similar to Schultze's " Halipetasus scaber." 



Cephea octostyla L. Agassiz. 



Medusa octostyla, Fokskal, 1775, Descrip-Anim. Itin. Orient, p. 106, No. iS, Icon., tab. 29. 



Medusa cephea, Linn4, (Gmclin) 1788, Systcma Natura:, Ed. 13, p. 3158. hion Medusa cephea, Forskal. 



Cephea cyctophora, Milne-Edwards, 1849, Cuvier's Regno animal illustre Zooph., planche 51, fig. 4. 



Cephea octostyla, .AdAssiz, L., 1862, Coat. Nat. Hist. U. S., vol. 4, p. 156. 



Stylorhiza octostyla, Haeckf.!., 1880, Syst. der Medusen, p. 613. 



{?) Stylorhlza polystyla, Haeckel, 1880, Syst. der Medusen, p. 613. 



Halipetasus scaber, Schultze, L. E., 1898, Denkschrift. Med. Nat. Gcsell., Jena, Bd. 8. p. 458, taf. 33, fign. 5 und 7. 



According to Haeckel and ForskSl the bell is 300 mm. wide, flatter than a hemisphere. 

 Surface ot exumbrella smooth, without a central dome, and without radiatine furrows. 8 

 rhopalia 50 to 60 ( .'') wide, flatly-rounded, marginal lappets. Rhopalar clefts shallow. Arm- 

 disk wider than bell-radius. 4 small subgenital ostia. 8 bifurcated mouth-arms 1.25 times 

 as long as bell-radius; the forks of each arm as long as undivided upper part of arm. 9 long, 

 stout filaments of uniform caliber arise apparently from the arm-disk. These are 1.5 times 

 as long as diameter of bell and end simply, without terminal knobs. In addition to these 

 filaments there are about 12 short, stout, swollen, club-shaped appendages between the mouths 

 on the lower sides of the arms. The color is blue and hyaline, .\rabian coast of the Red Sea. 



Forskal's description evidently refers to the medusa figured on his plate 29. not that of 

 plate 30 as stated by Niebuhr, who edited the plates of his work in 1776. While Forskal's 

 figure is remarkably good for its period, his description is too brief and vague to be of value. 

 I he description given above has therefore been mainly derived from a study of his figure. 



Haeckel's " Stylorhiza polystyla" from Singapore is described from a preserved and 

 damaged specimen. It is said to be 100 mm. wide with flailv rounded bell and 80 marginal 

 lappets. In each octant are 8 rectangular velar and 2 small oval ocular lappets. 4 subgenital 

 ostia hardly as wide as the columns between them. Mouth-arms nearly twice as long as bell- 

 radius; many times dichotomously branched, with 16 very long tubular appendages and 

 numerous vesicles upon long pedicels. 8 of the long appendages arise from the bases of the 

 arms and 8 from the crotches of the primary forks. This is probably identical with Forskal's 

 medusa. 



Many well-preserved specimens oi Cephea octostyla were obtained by the U. S. Fisheries 

 Bureau steamer Albatross at Jolo Anchorage, Philippine Islands, tropical Pacific, in February 

 and March, 1908. 



1 he bell of the large specimens is 90 mm. wide, exumhrella flat; rim \eitical, 20 mm. high. 

 Neither central dome nor coronal furrow, but there is a zone of numerous, low, wart-like 

 protuberances upon the exumbrella, leaving the center free. This wart-covered zone is about 

 40 mm. in diameter and 15 mm. wide, leaving a circular area about 10 mm. in diameter free 

 of warts at the center of the exumbrella. Other parts of the exumiirella are smooth. There 

 are 8 rhopalia set within fairly deep niches. These lack ocelli and have no exumbrella sensory 

 pits. There are about 72 indistinct lappets, 7 velar and 2 ocular lappets in each octant. These 



