Br. F. A. Bather — Notes on Yunnan Cystidea. 73 



The genotype is H. suhcylindrica (Barrande sub Aristocystites ?), and 

 for this the original of Barrande's pi. 13, figs. 1-4, is selected as 

 Holotype. The holotype of A.. ? yrandiscutum (Barrande, pi. 17, 

 fig. iii) should he referred to II suhcylindrica, and the two other 

 specimens of A. ? yrandiscutum (pi. 14, fig. 20, pi. 38, fig. 30) 

 revert to A. bohemica. These specimens were associated by Barrande 

 on account of a similarity in the basal attachment — a character of 

 individual adaptation, insufficient to distinguish them from the 

 species to which they are now referred. 



Calix sedgwicki Rouault, which was placed by me in the 

 Aristocystidas (1900), was, after examination of specimens, referred 

 by Jaekel (1899) to the Sphaeronidae. The adoral region remains 

 unknown, but the structure of the thecal plates shows some 

 resemblance to Sinocystis yunnanensis, viz., in the umbonal pustule, 

 and in the frequent radial arrangement of the diplopores on the 

 surrounding area of each plate. Jaekel, as previously mentioned 

 (vol. Y, p. 513), believes that the diplopores of Calix had a covering 

 of epistereom. Some specimens referred by various authors to Calix 

 may belong to Aristocystis; Calix sedgwicki itself may not be 

 generically separable from Codiacystis Jaekel (= Craterina Barr. 

 non Bory). 



Archegocystis Jaekel, with genotype A. desiderata (Barr.), may be 

 mentioned here because Jaekel is uncertain whether the pores are 

 diplopores or haplopores. Though found in the Lower -Ordovician 

 (D, 1, ry), it has five facet-bosses, each bearing five or six grooves, 

 each of which presumably was provided with a brachiole as in 

 Codiacystis. A hydropore-slit and gonopore are placed as in 

 Aristocystis. 



B. — Comparison with Megacystis (stun. IIolocystites, 

 Trema tooystis) . 



The fossils to which, at first sight, Sinocystis bears the strongest 

 resemblance, are undoubtedly those from the Silurian of N. America 

 which for many years passed under the name Holocystis {-ites). 

 Justifiably, therefore, Dr. Reed alludes to these in his account of 

 Ovocystis mansuyi, but to make the resemblances and the differences 

 clear it will be well to go into greater detail. 

 1. History of the Genus. 



The fossils referred to were first made known by James Hall, in 

 the form of internal casts from the Niagara Limestone of Bacine 

 in Wisconsin (1861, Ann. Rep. Geol. Surv. Wisconsin, p. 23; 1862, 

 Bep. Geol. Wisconsin, I, pp. 69 and 431, text-fig. 16/1 & 2). He 

 published figures but no description, and distinguished two species 

 under the names Caryocystites eylindricum (fig. 16/1) and 

 C. alternatum (fig. 16/2). In the 20th Report of the New York 

 State Museum, of which the earlier pages seem first to have been 

 issued in 1864, Hall established the new genus Holocystites (p. 311) 

 for the reception of these two species as well as the new species 

 H. abnormis, from Racine, and II. tvinchelli, H. scutellatus, and 

 H. ovatus from Waukesha, Wis. The complete Report was issued 

 (presumably in a limited edition) in January, 1865, and (more 

 freely) in 1867 ; a revised edition was published in 1870. By 1865 



