46 SHELVE DISTRICT 



II and 12 capillae per mm were counted respectively in o, i, o, 3, I and o specimens 

 from the Spy Wood Grit and in 1, 3, 3, 5, 1 and 1 specimens from the Rorrington 

 Flags. The ribbing of the Betton and Meadowtown specimens shows a similar range 

 in frequency and, although 3 valves from the Hope Shales, with counts of 10, 12 

 and 13 per mm, may be indicative of an older Schizomania with finer radial orna- 

 mentation, the differences are not significant at present. 



The Shropshire Schizomania is closely related to 5. filosa (Hall) which is known 

 principally from the younger Trentonian rocks of N. America (Cooper 1956 : 275). 

 No details are available on the variation in the general morphology of the American 

 species. But the Shropshire forms are distinguishable in possessing a rounded 

 rather than truncated posterior margin and a dorsal umbo which is not marginal : 

 and although no pedicle valves have yet been recovered, these differences in the 

 brachial valve seem sufficiently important to warrant the erection of a new 

 species. 



Table 27 



Statistics of the length (1) and maximum width (w) of n brachial valves from the Spy Wood Grit 

 (A) and the Rorrington Beds (B) of Schizocrania salopiensis sp. nov. 





A 



B 



n 



6 



20 



1 mm (var 1) 

 w mm (var w) 



r 

 a (var a) 



6-42 (9-842) 



7-23 (15-01) 



0-997 



1-2349 (0-00259) 



Table 28 



4-29 (5-432) 



5-i (7-58) 



0-986 



1-1813 (0-0022) 



Statistics of the length (1) and depth (th) of n brachial valves from the Spy Wood Grit (A) and the 

 Rorrington Beds (B) of Schizocrania salopiensis sp. nov. 





A 



B 



n 



1 mm (var 1) 



th mm (var th) 



r 

 a (var a) 



7 



6-71 (8-822) 



2-24 (1-233) 



0-914 



0-3739 (0-0046) 



9 



4-i (3-74) 



077 (0-145) 



0-971 



0-1969 (0-00032) 



Table 29 



Statistics of the length (1) and length of the posterior adductor scars measured from the umbo 

 (sc) of n brachial valves from the Spy Wood Grit and the Rorrington Beds of Schizocrania 



salopiensis sp. nov. 



A B 



n 4 10 



1 mm (var 1) 6-62 (14-23) 7-28 (12-984) 



s"c mm (var sc) 2-05(1-397) 2-07(1-193) 



r 0-997 0-952 



a (var a) 0-3133 (0-00033) 0-3031 (0-00107) 



