512 Dr. F. A. Batlier — Notes on Yunnan Cystidea. 



(specimen I, 8), and as it grows upwards there is certainly a tendency 

 for the epistereom to block the pores, but I was unable to' convince 

 myself that it ever actually succeeded (Text-fig. 5). In S. ytmnattensis, 

 where the pore-pairs are more numerous than in S. loc%yi, they have, 

 for the sake of space, to assume a more regular arrangement, and so 

 the long axis of each elevation is on a line radiating from the umbo 

 of the plate; but they are not in continuous lines. At the umbo of 

 each plate the growth of the elevations is such that the "whole 

 epistereom of the umbo is often raised into a kind of turret 

 surrounding a few diplopores. These turrets were only found 

 preserved on those regions of the theca from whicli the matrix had 

 not been weathered away ; probably they had been worn down in 

 the other regions. On other parts of the plate there are sometimes 

 elevations similar but subsidiary to that at the umbo (e.g. I, 1) ; in 

 some cases a plate with about five of these in a circlet round the 

 umbonal turret resembles a cidarid plate with its primary and 

 secondary tubercles. Excessive growth of epistereom, especially in 

 the turrets, may perhaps close the pores occasionally; but I could 

 not be any more sure that it did so in this species than in 8. loczyi. 



5 6 7 



Fig. 5. — Sinocystis loczyi: a group of tubercles bearing open diplopores, seen 



from the side, on a fragment extracted from soft matrix accompanying 



specimen I, 8. x f . 

 Fig. 6. — Sinocystis mansuyi : an elevation bearing a diplopore, seen from 



above and from the side, on specimen II, 5. x f-. 

 Fig. 7. — A root attached to the theca of Sinocystis mansuyi, II, 6, a little 



above its base, x f . 



In 0. mansuyi the fairly numerous but irregularly distributed 

 diplopores appear in some cases (e.g. II, 2) to be sunk directly through 

 the test, without either elevation or peripodium. This appearance 

 may, however, be due to wearing down; for in II, 8, each pore-pair 

 is surrounded by a slight elevation dying away into the test, and in 

 well-preserved tracts of II, 5 the elevation is still more definite and 

 rises higher between the pores of each pair so that the openings lie 

 on its shoulders (Text-fig. 6). In unworn tracts of II, 9, 10, and II, 

 the elevation is relatively high and well-defined, and occasionally 

 suggests a tendency to be so directed that both openings face up- 

 wards, i.e. in an adoral direction (especially in II, 9). In this 

 species the epistereom does not grow up round the pores so strongly 

 as in S. yunna7iensis or even S. loczyi, and there is never any 

 appearance of blocking. 



Although I was unable to prove the closing of any diplopores in 

 these fossils. Dr. Heed presumably has satisfied himself that it does 

 occur in both his species of Sinocystis. If so, it should probably be 

 regarded as a character of old age, and not as diagnostic of a genus. 

 It is difficult to believe that the closing of true diplopores by 



