484 



G. C. Crick — Orthocerata from North China. 



In this genus the shell is much compressed, the chambers shallow, 

 the test thin, the siphuncle nummuloidal and placed near one surface. 

 According to Hall this fossil occurs in the Black Eiver Limestone 

 (Ordovician) in New York State, "usually appearing upon the 

 weathered surface of rocks, with the ventral or dorsal side exposed, 

 and presenting a broad surface with extended septa and central 

 siphon." 



1 



.e\ 



Fig. 3. — Gonioceras aoiceps. a. Much weathered fragment, dl•a^vn from a specuuea 

 in the National Collection (No. C 4079) ; natural size. h. Section showing 

 position of siphuncle. Ordovician (Black River Formation) : "Watertown, 

 Jefferson County, New York State. (After Foord.) 



A third species, in a totally distinct matrix, is represented by 

 a broken portion of a longitudinal slab or polished section of the 

 well-known Orthoceras chinense, Foord,^ of which the British Museum 

 contains several excellent examples. Ortlioceras chinense, Foord — 

 the true 'Pagoda-stone' of the Chinese — appears to be a well- 

 marked species from the Devonian of China, and as it is much 

 sought after for cutting and polishing in order to be mounted and 

 form ornamental screens or panels, it has become an article of 

 commerce, and consequently may now be met with in almost any 

 part of China. The name ' Pagoda-stone,' which is generally given 

 to the cut and polished sections of Orthoceras chinense by the Chinese, 

 is said to arise from the popular belief that they are formed in the 

 earth wherever the tower of the pagoda casts its shadow upon 

 the ground. 



' A. H. Foord: Cat. Foss. Ceph. Brit. Mus., pt. i (188S), p. 100. 



