ORDOVICIAN BRACHIOPODA 87 



Superfamily ENTELETACEA Waagen 1884 



Family SCHIZOPHORIIDAE Schuchert & Le Vene 1929 



Subfamily DRABOVIINAE Havlicek 1950 



DRABOVIA Havlicek 1950 



Drabovia cf. fascicostata Havlicek 



(PL 14, figs. 14-16, 18, 19) 



1950 Drabovia fascicostata Havlicek : 15. 

 1950 Drabovia fascicostatata Havlicek : 47. 

 1950 Drabovia fascicostata Havlicek : 47. 



Diagnosis. Ventribiconvex Drabovia ornamented by fascicostellae with about 

 5 ribs per mm, 5 mm antero-medially of dorsal umbo. 



Description. Semi-elliptical, ventribiconvex, sulcate Drabovia, with orthogonal 

 cardinal angles of young shells becoming obtuse in mature growth stages so that the 

 hinge line is less than the maximum width of the shell ; carinate pedicle valve 33% 

 as deep as long, brachial valve 73% as long as wide and 15% as deep as long (the 

 mean for 4 valves) with an evenly concave sulcus and evenly convex sides ; ventral 

 interarea relatively short, curved apsacline, dorsal interarea very short anacline, 

 delthyrium and notothyrium open ; radial ornamentation fascicostellate, divided 

 into sectors by capillae, with counts of 6 and 5 ribs per mm occurring 5 mm antero- 

 medially of the umbones of 1 and 4 brachial valves respectively, costellae branching 

 internally in valves up to 5 mm long with ia, 2a, 3a and 4a occurring early but with 

 3a°)3ala, 3a°)3C and 4a°)4b present (costellae insertion code of Bancroft, 1945). 



Cardinal process with a very small bulbous myophore and relatively long linear 

 shaft, becoming thicker in mature valves, continuous with median ridge-like pos- 

 terior part of sulcus ; brachiophores short, acutely divergent, bases 17% as long as 

 the brachial valve, parallel or convergent with the median ridge, sockets rarely 

 defined by fulcral plates ; muscle scar unknown. 



Teeth small supported by slightly divergent dental plates extending forward for 

 16% the length of the pedicle valve ; ventral muscle field subcordate with broad 

 adductor scar bounded laterally by lobate diductor scars impressed anteriorly for 

 about one-quarter the pedicle valve length. 



Figured material. 



length width (mm) 

 External and internal moulds of brachial valve 



(BB 35316a, b) 4-0 4-8 



External and internal moulds of brachial valve 



(BB 35317a, b) 4-5 9-4 



External and internal moulds of pedicle valve (BB 35318a, b) 4-5 5*2 



External and internal moulds of pedicle valve (BB 35319a, b) 5-5 7-5 



Horizon and locality. Spy Wood Grit exposed 1100 yds NNE of Rorrington 

 (GridRef. S J 303015). 



