Dr. F. A. Bather — Notes on Yunnan Cystidea. 537 



The actual Base of Attachment is well shown in I, 2 and 6; it is 

 slightly expanded, A-ery slightly excavate, and in I, 5 is extended in 

 tlie anal plane. The "stalk" is not a specialized stem, but merely 

 a narrowing of the theca; in I, 6 and 7, however, the plates in the 

 lower part of the theca are arranged transversely ; and this is 

 marked, especially in I, 6, by a transverse alignment of the pore- 

 tubercles. 



There is little to add to Dr. Reed's full account of the plates and 

 their structure. The diameters of the plates in I, 1 range from 

 •7 mm. to 65 mm. There is an occasional tendency for a large plate 

 to be surrounded by smaller ones. The diplopores have already 

 been discussed (p. 512, Text-fig. 5). The inner face and the 

 margins of the plates are not exposed. 



Sinocystis yunnanensis Reed. 



Of the four specimens mentioned by Dr. Reed, the three figured 

 ones have been studied, viz. I, 9, 10, and II, 1. Of these I, 10 is 

 certainly identical with No. II in Reed's table of measurements ; 

 but, since his measurements are estimated, his No. I cannot be 

 identified. "The largest," he says, "is the best preserved"; 

 probably this is I, 9. But II, 1 is hereby selected as Holotype, 

 because it seems to show the openings more clearly than do the 

 others. 



The following are actual measurements in millimetres : — 



Peristome plane . . ? 90° ?90° 105° 



(For explanation of angles, see under S. loczyi.) 



The cover-plates are relatively large, irregularly triangular, 

 alternating, and interlocking. 



Hydropore-slit concave towards peristome ; its middle line about 

 3"2 mm. from middle line of peristome in II, .1, a little further in I, 9. 



The Anal pyramid is seen in II, 1, its centre 20 mm. from edge of 

 peristome; diameter of hexagon, side to side, 5*5 mm. ; height above 

 general surface, about 2*2 mm. 



Gonopore seen in II, 1, at 7*7 mm. to left of anal centre. 



The Basal Attachment is seen only in I, 10 ; it is somewhat 

 cylindricallj' excavate along its greater diameter, which corresponds 

 approximately with the shorter diameter of the theca and with the 

 peristome plane. The theca is rather sharply bent over on its stalk, 

 apparently to the left, so that there was a mechanical advantage in 

 this shape of the attachment. 



The phites may attain a diameter of about 7 mm. in the larger 

 specimens. They are about "7 mm. thick in the middle region of 

 II, 1. Their margins are irregularly creuelate, especially on the 

 inside edge. The crenelloe do not appear on the outer suture; they 

 are in no relation to the diplopores. 



