100 



MK.WS.E OF THK WORLD. 



Billard has studied the variations of the medusa at the Bay de la Hougue near St. Vaast 

 on the northwestern coast of Fiance. Here he found that among 50 medusae 5 had 6 radial- 

 canals, 4 had 7, 39 had 8, I had 9, o had 10, I had u. In the case of the 39 medusae with 

 8 radial-canals, 36 had 2 simple and 3 bifurcated canals, as in the Naples medusa. 



Miillei, 1908, has studied the origin and structure of the ova in this medusa. The eggs 

 are small and rounded and widely scattered in the gonad, for the successful eggs devour 

 the weaker in the ovary. The ooplasma is sparsely vacuolated and there is very little yolk. 

 53- 55- 



54- 



";; .- Hydroid of ClaJonema raiiiatum, after Hincks, in British Hydroid Zoophytes. 

 Showing growth-habit of hydroid and enlarged view of single polypite. 

 Fir.. 54. ClaJonema raJiatum, after Allman, in Ray Society, 1871-72. Budding 



hydroid anil mature me lusa. 

 Fi<;. 55. Medusa of C.lailontma rnJiatum, after Hincks, in British Hydroid Zoophytes. 



The hydroid of Clndoncinti radiattitn isStaurn/ia raJiatum Dujardin = CAndonema radiatum 

 Hincks. 



The hydrorhiza is a slender, creeping filament from which the hydranths arise at inter- 

 vals. These hydranths are either simple, unbranched, and about 2.5 mm. high, or are borne 

 upon slightly branching stems 12 to 25 mm. high. The hydranths are club-shaped and 

 have 2 alternating verticils, each circlet consisting of 4 tentacles. The circlet near the mouth 

 is composed of long tentacles, each of which ends in a knob, while the circlet at the base of 

 the hvdranth consists of 4 very short, simple, unbranched, filiform tentacles which alternate 

 with (i. e. are upon meridians 45 apart from) the oral circlet. The medusae bud out singly 

 from the sides of the polypite at a short distance above the basal circlet of tentacles. The 



