334 ERNEST WARREN. 



median one is nearly vertical. The hydrotheca possesses a 

 very long conspicuous spine (figs. 28, 29, sj^l.), wliicli is cm-ved 

 upwards. The intra-thecal ridge is not very strongly 

 developed; it occurs rather below the middle of the hydro- 

 theca. 



Measured from the side, height 0*226 mm., breadth 

 0'166 mm.; from the front, breadth at the middle, 0*123 mm. ; 

 diameter of mouth 0*25o mm. Length of spine (t. e. length 

 of the arc) 0*166 mm, 



Hydranth. — 10-12 tentacles. 



GrONOSOME. — Male and female corbulte occur on diiferent 

 shoots and probably on different colonies ; they differ con- 

 siderably in shape, the male being much longer and thinner. 

 The female corbula consists of about nine pairs of leaflets 

 (fig. 31), which fuse together into a continuous sheet by their 

 inner margins. The outer margins are provided with a close- 

 set row of cylindrical nematophores. From the base of each 

 leaflet there arises a lateral leaflet with a row of nematophores 

 along each edge. The rhachis is divided into regular inter- 

 nodes. The gonangia are arranged in a single row. 



In the male corbula there may be 13-15 leaflets (fig. 30) ; 

 the lateral leaflets are relatively shorter than in the female, 

 and almost disappear at the distal end. 



Looked at from above the leaflets of the male corbula are 

 less closely united together by a web than in the case of the 

 female corbula ; and this observation agrees with that of 

 Torrey and Martin,^ to the effect that a sexual dimorphism is 

 exhibited iii Aglaophenia by the male corbula being more 

 or less open above, owing to the incomplete fusion of con- 

 tiguous leaflets at their tips. 



The peduncles of the corbulas carry two hydrotheca?. 



Length of female corbula 3-4 mm., depth 1*11 mm., width 

 from above 0*82 mm. 



Length of male 4-5 mm., depth 0"75 mm., width from above 

 0*71 mm. 



' Torrey, H. B., and Martin, Ann, " Sexual Dimorphism in Aglao- 

 phenia," University of California Publications, 'Zoology,' vol. iii. No. 

 4, 1906, p. 50. 



