177 



taken for an ,itr_r/>a rather than iu\ Atf/jris: for the shell of an Atrypa is 

 ■' radially plicated,^' " while there is hardly any record of such radial ribs in 

 Af/ryris. 



Several specimens, however, were cut and polished in the course of the 

 study, and it was proved that these forms possess spirals inside which are 

 directed laterally as in the case of . lt//_v> is, not dorso-medially as in the forms 

 belonging to the group of or the subfamily Atrypina: Waagen. 



Now, there are other groups, in which the shells are radially plicated, 

 spirals laterally directed, and beak perforated, namely, those classified as be- 

 longing to the funily Rhynchospiridas Hall and Clarke.-' Of those genera 

 placed in this famil\- by Scmuchert, RIirncho:spira Hall, l') cinatospi) a Hall, 

 and Pararsy.^'a Hall and Clarke an^ especially resemblant to the Chinese 

 fossils. Thus the writer Avas quite at a loss to find the position of these peculiar - 

 fossils in the known forms of Brachiopoda : he was very much inclined to 

 regard them as new species of a certain one of the above mentioned genera. 



Another course was tried by the writer in this direction. The artificial 

 key to the genera of Brachiopoda schemed by Grabau and Shiimer^' was 

 scanned by him, and the Chinese fossils were found to fall in either of the two 

 genera, Pararj.yg'a or Trcmafosf>ira . First of all the shell has a marginal 

 beak, but laclcs a cardinal area : its hinge-line is somewhat straight but very 

 short. Within the category having these characteristics the fossils are sub- 

 divided into trimelloid, Hnguloid, pentameroid, rhynchonelloid and terebra- 

 tuloid or athyroid forms. The present fossil is athyroid in outline and 

 consequently belongs to the last group. Furthermore the shell is radially 

 striated with a sinus and a fold. The beak of the pedicle valve is truncated b\- 

 a foramen, although the shell is not so very transverse as in Pnrazyga or 

 Ti ciiiatospira. It is not clear whether the plications or striae possess minute 

 spines or not. 



This result is cjuite coincident with the last, and it seems that this is the 

 position t(> which the Chinese fossils may most adequately be ascribed. 



i) ScHucHERT: — Eastman's Text-book of Paleontology, vol, L, p. 409. 1913. 



1) SCHUCHERT: — op. cit., p. 413. 



3) Grabau and Shimer; — North American Index Fossils, vol. L, p. 177-1S7. 1919. 



