156 



really the same thing as Sp. cuspidata of the latter. Another ix>ssible inter- 

 pretation is that Davidson could not detect the perforation in his own ex- 



-amples, although it was really present. 



At any rate Spirifcr and Cyrtia may represent different groups. They 

 may not be two distinct genera, as Schuchert considers them to be, but they 

 are not likely to be united as one genus as in the Grundzage der Palaeon- 

 tologie of ZiTTEL. As to the above incident of Davidson and Woodv^ard, the 

 writer thinks that the first of the two explanations of the dilemma is the more 

 probable ; for, Davidson's material oi Sp. cuspidata seems not at all so insuf- 

 ficient as to have led him to overlook the perforation of the pseudodeltidium. 

 With regard to the original fossil of De Koninck, Scupin's conclusion 

 Die Gattung (bezw. Untergattung) Cyrtia ist daher einzuziehen und die 



"bisher unter diesen Namen (in DAViDSONschem Sinne) vereinigten Formen 

 sind der Gattung Spirifcr s. str. zuzurechnen," may hold on one hand. But if 

 the Chinese form described by Davidson is to bear the name Cyrtia vinrchi- 



.soniana, then the case is fundamentally different. Cyrtia murchisojiiana and 



.Spirifcr disjiinctus are two independent forms although they are very closely 

 related to each other. Of course the genus Cyrtia may be united to Spirifcr, 

 as Scupin and others think, if the specie of Spirifcr without exception have 

 a perforated pseudodeltidium. This, however, cannot be said to be decided 



.at present. 



Cyrtia viurcJiisoniana was originally denominated a Spirifcr by De 

 Koninck, and it was Davidson who removed it to the genus Cyrtia of Dal- 

 man. Davidson who at one time recognized Cyrtia imircJdsoniana as a form 

 independent of Spirifcr disfiuictiis, eleven years later regarded it as synony- 

 mous with the latter In this case there may have been a large number of 

 specimens of a form called Sp. DiurcJiisoniana by De Koninck, some of which 

 were different from, while the others were coincident with, Sp. disjutictiis 

 Sow. Those with perforated pseudodeltidium may have been considered as 

 Cyrtia; w^hile those without it may have been identified with the Spirifer. 

 In his monograph Davidson says that Sp. murchisoniana, with several other 

 forms, may be a mere synonym or a variation of Sp. disjiinctus. He, however, 

 "does not mention his own Cyrtia miirchisoniana from China among the syn-. 



