1 88 



thickness respectively. Ail of the specimens of this species collected by 

 Yabe in Gerolstein, Eifel, are much smaller than those from China. Of them 

 the largest measures 14 mm., hy 17 mm. by 12 mm., but all the others are 

 remarkably smaller. Kayser's specimens (^^1871) measure some 14 mm., by 

 18 mm., by 12.5 mm. Extraordinarily large specimens from Indo-China were 

 mentioned as a species ver\' near to the present one. In some respects they 

 indeed quite closch' resemble Kliyiiclionclla f'arallclcpipcda. Neither the 

 description nor the figures, however, being very clear, the true nature of the 

 Indo-Chinese fossils is quite obscure. The present writer is not inclined to 

 include these forms in the species now under consideration. 



That rci'fbratiila siibco)diyoriiiis Scunl'R is identical with Rlt. parallclc- 

 pipcda has long .since been admitted by palaeontologists. The writer, how- 

 ever, hesitates to include the specimens represented by Sciinur'.s figures 6d, 

 e, f, g. Although the author notices that these last figures show the " Gc- 

 hiiuse iunger Thiere," their form is somewhat too divergent from the typical 

 form of the species. 



LoKWE. in his paper above cjuoted, includes 13avidson'.s .A'//, hiiplcxa in 

 his Rli. piirallclcpipcda, for which the reason is quite obscure to the present 

 writer. The former shows no sign at all of the peculiarities of the latter 

 .species. Davidson uses for this species the name Rli. priinipilaris instead of 

 Rli. p(irall( lcpipi-dn, regarding the two as synonymous. If they were really 

 identical. Da\]D.sox"s nomenclature ought to be regarded as justified. 

 Hovvex er, on examining, the figures of the former species drawn by Schnur, 

 the writer finds that Da\ ipson's circumscription of J\]i. priiidpiLaTis was not 

 correct. Schnur's idea of RJi. priviipilari^^ must no doubt hold good, for 

 Lo]:\\ E does not cite it in the synonymy given in his paper. Kavser, also, in 

 all of his papers excludes it from the .synon}'m\\ Thus Rli. f>iu allclcpipcda 

 must hold its position in the genus of Rhyiichoiu-lla as an independent species. 

 In Rli. priinipilaris the ribs dichotomize, or trichotomize while they are 

 usually single throughout in the present species. Whidborne, however, re- 

 marks that there are some specimens in which the ribs occasionally are dicho- 

 tomous in a very subordinate degree, and he doubts the idea of Kavser^' that 

 the two forms are separated in this point. 



i) Kayser: — op. cit., pp. 510 and 512. 1871. 



