ORDOVICIAN BRACHIOPODA 115 



5. salteri of 5 per mm, 5 mm antero-medially of the umbo, are sharper and less uni- 

 formly multicostellate. This difference is the only important one observed because 

 the apparent greater convexity and sulcation are attributable to post-diagenetic 

 deformation of the specimen. When more is known about ribbing variation in 

 Salopia the difference may prove to have no systematic status ; meanwhile it seems 

 advisable not to allocate the specimens to any described species. 



Suborder CLITAMBONITIDINA Opik 1934 



Superfamily GONAMBONITACEA Schuchert & Cooper 1931 



Family GONAMBONITIDAE Schuchert & Cooper 1931 



Subfamily ANOMALORTHINAE Ulrich & Cooper 1936 



OSLOGONITES Opik 1939 



Oslogonites ? sp. 



(PI. 19, figs. 12, 13) 



An external and incomplete internal mould of a brachial valve (BB 35326a, b) 

 about 2 mm long and 3-5 mm wide, from the Mytton Flags exposed along the side 

 of the footpath at road level, 1100 yds NNW of Wood House (Grid Ref. SJ 338003), 

 is believed to represent the remains of an immature specimen of Oslogonites Opik. 

 The valve was semicircular in outline and evenly concave in profile with acute 

 cardinal angles. It was ornamented by intercalated costellae, numbering 6 per mm 

 anteriorly, with every fourth or fifth thickened to delineate a series of sectors in an 

 unequally parvicostellate fashion. Enough of the internal mould is preserved to 

 show that the socket ridges were acutely disposed to the hinge-line to define narrow 

 sockets and joined medially in a small ridge which was not differentiated into a 

 cardinal process. There was no notothyrial platform nor median ridge, but a pair 

 of curved septa occurred in the area normally occupied by adductor scars. 



The concavity of the brachial valve and the unequally parvicostellate nature of its 

 radial ornamentation suggest either a strophomenidine or a clitambonitidine affinity. 

 However, the disposition of the socket ridges favour its identification as a clitam- 

 bonitidine ; and since the anomalous lack of a notothyrial platform may be attribut- 

 able to the immaturity of the valve, the specimen is best assigned to Oslogonites. In 

 fact the Shelve brachial valve probably resembled that of Oslogonites costellatus 

 (Opik 1939 : 134) from the Arenigian expansus Shale of Norway except that it was 

 more concave and its parvicostellate ornamentation more strongly differentiated 

 into sectors. 



Family KULLERVOIDAE Opik 1934 



KULLERVO Opik 1932 



Kullervo sp. 



(PI. 19, figs. 14, 15) 



The only kullervoidid represented in the Whittard collection consists of a 

 fractured internal mould and an incomplete complementary external mould of a 



