Dr. F. A. Bather — Notes on Yunnan Cystidea. 513 



epistereom can ever have been a normal character of the adult in any 

 species: the structures seem so clearly adapted for the passage of 

 some aerating organs (papulae) through the test; and the very fact 

 that the epistereom does grow up in tubercles and turrets indicates 

 the constant outward extension of those organs. In opposition to 

 tliis view, the only previous evidence of weight has been Professor 

 0. Jaekel's account of a thin reticular layer covering diplopores in 

 a fragment of " Calix sedgewichi^^ from Bussaco (1899, Stammes- 

 gesch. d. Pelmatozoen., p. 72), an observation as yet isolated and 

 unconfirmed (see, however, discussion of Trematocystis in Part III). 



The last point of difference mentioned in Dr. Heed's diagnoses is 

 thus expressed : Sinocystis, " No food-grooves on surface"; Ovocystis, 

 " Surface of theca provided with irregular shallow food-grooves 

 meandering between plates, with local traces of stronger meridional 

 and concentric or spiral grooves." It is, as previously stated, the 

 case that Sinocystis, no less than Ovocystis, has short epithecal 

 food-grooves leading from the corners of the peristome to the 

 brachiole-facets. But certainly it has no others, and that is what 

 Dr. Heed means. If Ovocystis has these meandering food-grooves in 

 addition, it differs in this respect not merely from Sinocystis but 

 from every pelmatozoon yet described, and is a remarkable form 

 indeed. 



Unfortunately I was not acquainted with Dr. Heed's observations 

 till some time after the specimens had been returned to Calcutta. 

 I had, however, carefully examined, under a binocular dissecting 

 microscope, the whole surface of the ten specimens lent to tlie 

 Museum,, and it is difficult to believe that such unusual structures 

 could have escaped notice. I have subsequently examined the 

 plaster-casts carefully made by Mr. F. 0. Barlow, and can see 

 between the plates nothing that suggests a food-groove. Dr. Heed 

 in his description (p. 8) certainly adds that the grooves are 

 "obscure", but he also gives a fairly definite account of their 

 •course. He distinguishes three kinds: (1) "shallow . . . grooves 

 irregularly meandering along the suture-lines . . . and frequently 

 uniting"; (2) "one or more stronger sinuous longitudinal trunks 

 running meridionally down anterior face" [= posterior side]; 

 (3) "one or more concentric or obscurely spiral sinuous trunks on 

 the posterior [= anterior] face in the lower third." He figures no 

 details of these grooves, and not one of Mr. Brock's enlarged 

 drawings of the surface shows the smallest trace of them. Only 

 fig. 5 on pi. II, which represents a theca with weathered and 

 imperfectly preserved surface, is said to show "traces of spiral 

 grooves " on the " posterior side ". Actually the view is of the right 

 side, the theca being compressed in the anal plane, and the hydropore 

 lying under a prominence shown at the top of the figure about 1 cm. 

 to left of the median line. The post-mortem compression of the 

 theca has pushed the greater part of this right side in, so that there 

 is a sharp bend or crack down the anterior edge (right hand of 

 figure); and on the upper posterior edge (left of figure) the plates 

 are pushed slightly under those of the other and less compressed 

 half of the theca. The depression thus produced is continued as an 



DECADE VI.— VOL. V. — NO. XI. 33 



