508 Dr. F. A. Bather — Notes on Yunnan Cystidea. 



care. Although Dr. Heed has published good figures, drawn with 

 Mr. T. A. Brock's usual exactitude, and descriptions, on the fulness 

 of which he will perhaps allow me to compliment him, neverthe- 

 less the notes made by me, when still unacquainted with his 

 valuable work or with the views therein expressed, do contain 

 supplementary matter, which it seems better to publish now rather 

 than to reserve for some revision in an uncertain future. 



Orientation. 

 To avoid confusion, it is necessary to explain that the terminology 

 and orientation here employed are the same as those used by me in 

 describing the cystids from the Northern Shan States (1906, 

 Palaeont. Ind., kt.s., vol. II, Mem. 3), also in Lankester's "Treatise 

 on Zoology" (1900), and elsewhere. As regards the terminology of 

 the various parts and organs, Dr. Reed and I are in general agree- 

 ment ; but the orientation adopted by Dr. Eeed is unfamiliar. To 



jKskrior 





oral 

 p,QLe 



I 



^4r u^ 





[saaltfyl ^ 





anterior 



posh 



enor 



rwy 



Fig. 1. — A diagram of the adoral face of a simple five-rayed Pelmatozoon, 

 showing peristome, hydropore, gonopore, and periproct ; the orientation 

 indicated according to F. E. Cowper Eeed. 



Fig. 2. — The same ; the orientation indicated according to F. A. Bather. 



meet the difficulty that I found in interpreting it, Dr. Reed has 

 kindly marked his main lines on the accompanying diagrams 

 (figs. 1 and 3), beside which my own scheme (figs. 2 and 4) is placed 

 for comparison. In both cases the 'vertical axis' runs from the 

 oral centre (my 'oral pole') to the centre of the base (my 'apical 

 pole '), and all the diagrams are viewed from above the oral pole. 



Prom his diagrams and letters it appears that the basis of 

 Dr. Reed's scheme is the ' sagittal plane ', which he takes as passing 

 through the vertical axis in the direction of the mouth-extension, 

 or, in a normal five-rayed form, between the pair of rays enclosing 

 the hydropore [' bivium '] and the remaining three rays [' trivium ']. 

 The * antero-posterior plane' of Dr. Reed cuts the sagittal plane at 

 right angles on the vertical axis ; the anterior face of the theca is 

 that on which the hydropore lies, and (usually) the anus. 



