2o6 



GiRTV gave no distinct name whatever, but numbered it 6 in his table This 

 is the group which Schellwiev placed in the genus Orthothetes of Waagen^* 

 (i.e. SchucJicrtclla of Giktv), but must be different from the named genus of 

 GiRTv's circumscription. With regard to the internal structure of the fossil 

 Frech observes that it " zeigt zwei kraftge divergirende Zahnstiitzen, die nicht 

 sehr weit in die Schale hineinreichen.^'" Whether his " Zahnstiitzen " repre- 

 sent the same thing as are in general called the dental plates is not quite 

 certain, yet at all events, the Chinese fossil really has such a structure as 

 Frech observed. 



If, therefore, Girtv's classification is authoritative, then the present fossil 

 must not be regarded as an OrtJiotctcs but it would, together with several 

 forms in Schellwien's collection^' form a new group, such as was numbered 6 

 by GiRTV. No new or better subgeneric name is here proposed because it 

 belongs to Girtv's work, but the writer follows Frech's expression of 

 Or that etc s crcnistria. 



Though different from the ordinar}' forms, the Chinese fossil finds equi- 

 valents in some of the old known exemples of the crenistrlated species 

 of Ortliotctcs. Thus, for instance, if one supposes a specimen in Davidson's 

 monograph (pi. XXVII., fig. 9) to possess the interior features represented 

 by figures 5 and 6 in the plate XXVI., it will be the equal of the Chinese 

 species now being considered. Another form remarkably allied to the latter 

 is Orthothetes crcnistria Phill. var. Kellii M'Cov which has been described and 

 illustrated by von Arthaber from Armenia. As far as the external form is con- 

 cerned,-for the interior is inaccessible-thc two forms, the Chinese and Armenian, 

 are almost coincident. There must, however, be a reason for Frech's having 

 identified or even compared them in the work describing Chinese fossils. He 

 was no doubt well acquainted with the Armenian form. Therefore, although 

 M'Cov's variety far more closely resembles to the Chinese fossil than the 



1) E. ScHEi LWiEN: — Beitr. z. Systematik d. Strophomeniden d. ob. PalaeDzoicum. Neues 

 Jahrb. igoi, I., p. 6. 



2) Richthofen's China, vol. V., p. 77. 



3) E. SCHELLWIEN: — 1. C. 



4) F. Fr5Ch and Arthaber: — Palaeozoicum in Hocharmeinen und Persien, p. 200. 19 co. 



