.158 



could have been constructed from the examination of such unfavourable 

 examples. At any rate, both the forms of C. nmrchisoniana from China 

 (Davidson and KAVSER)and from the Ural are regarded as synonymous by him. 

 In his description it is stated, " Der Schlossrand ist erheblich kiirzer als die 

 Maximalbreite der Schale," while with the Uralian form this is by no means 

 the case. The hinge-line is, in the latter fossils, subequal or equal to the 

 maximum width of the shell just as in Lo ewe's Sp. brodi. After having 

 said that Sp. inarcJdsoniamis is distinguished from the group of Sp. vernciiili, 

 by its having among other points a perforated pseudodeltidium, Loewe adds 

 that these two forms are easily confused, " da die Beobachtung des Pseudo- 

 deltidiums nur bei besonders gut erhaltenen Exemplaren moglich ist.'' But 

 this cannot be accepted as a reason for bringing together the Chinese and the 

 Russian forms. He had better have put Tschernyschew's fossil in the syn- 

 onymy of his Sp. brodi. 



Also among a small number of specimens purchased by Prof Y. Yabe in 

 China there are forms representing the type of Cyrtia ninrcldsoniana of 

 Davidson, Kayser or Pellizzari. Thus the existence of Cyrtia murchi- 

 of Davidson's circumscription has been proved by the writer to be 

 real. Gosselet says " Le Cyrtia MiircJusoiiiana ne differe guere du 

 Spirifcr Vernciiili que par des details d'organisation interne et particuliere- 

 ment par les plaques dentaires." Similar things have been said by many 

 other palaeontologists, as one can find in such a paper as that above cited. 

 As to this point the writer cannot say much, because he has not been able to 

 examine the internal features of the fossil. This can be regarded as est- 

 ablished only after many of the specimens of the group or groups have been 

 studied minutely. There may be every stage of transition among them, just 

 as in the case of morphological variations. 



