Dr. F. A. Bather — Notes on Yunnan Cystidea. 539 



The cover-plates are perhaps a trifle heavier than in the other two 

 species, and are swollen. A section across the grooves is afforded 

 by II, 7 (Text-fig. 12). 



The Hydropore-slit (Text-fig. 13) is almost straight, lias thickened 

 edges, and the lumen expands slightly at the two ends (II, 2, 8, 9) ; 

 in 5 it is covered by an attached object like the lower valve of a 

 brachiopod ; and in 10 it is crushed close up to the peristome. 

 Dr. Reed describes it as "parallel to the mouth in a line joining the 

 right and left anterior [i.e. posterior] oral bosses". It would 

 perhaps be even more e.xact to substitute the words " brachiole 

 facets" for " oral bosses", and to note that the line joining them is 

 not c[uite parallel to the peristome, but further from it on the left 

 side. Also the hydropore approaches this left end, and thus its 

 deviation from perfect symmetry Avith reference to the peristome is 

 in the direction of symmetry with reference to the left anterior 

 food-groove. The bearing of this on the nature of the primitive 

 symmetry is the same as in S. loczi/i (see p. 535). 



The length of the slit is 4-5 mm. in II, 2; 2-3 mm. in II, 6; 

 •9 mm. in II, 7; 3-8 mm. in II, 8; 4-4 mm. in II, 9. Dr. lieed's 

 numbers are presumably over-all measurements. 



The Anal pyramid, according to Dr. Heed, is pentagonal. No 

 doubt this is correct for most of the specimens, but in the figured 

 specimens it was not so clear to me as to Dr. Reed and Mr. Brock. 

 My notes run: "In II, 8, about 16mm. from peristome, hexagonal, 

 but covered by a base witli stem 4 mm. long, 6-1 mm. wide below, 

 3'4mm. wide above ; diameter of pyramid, side to side, ca. 5-7 mm. 

 In II, 6, 10 mm. from peristome, ?hexagonal or pentagonal, diameter 

 ca. 5 mm., rather elevated — say, 1-3 mm. Elevated about I'omm. 

 in II, 7." 



The Gonopore lies to the left of the anus, distant from the anal 

 centre by 6-6 mm. in II, 6; ca. 9 mm. in II, 8. In 8 it is elevated 

 above the general surface ca. 1-5 mm. and has a diameter at the top 

 of l"6mm. The diameter of the lumen is ca. 1mm. in II, 8; 

 •6 mm. in II, 5 and 6. In 6 the lumen is clearly pentagonal. 



The stem-like appearance of the Base is rather more pronounced 

 in such specimens as II, 2 and 6 than it is in S. loczyi; but it is 

 approached by S.yunnaiiensis, I, 10. Owing to its sudden contraction 

 and projection from the egg-shaped theca, it has been broken off in 

 most of the (figured) specimens. This enables one to give the 

 following additional measurements in millimetres: — 



Specimen .... 

 Thickness of plates . 

 Diameter of lumen 



From these it follows that the plates increase in thickness as the 

 lumen contracts towards the distal end. 



The base in II, 11 (see Reed's figure) is built of five sub-equal 

 plates, about 3 mm. high, slightly broken below. These are 

 succeeded by a circlet of seven plates. 



The thickness of the plates, as measured in II, 10, a little above 

 the base, is '5 mm. The plates are described fully, and figured 



