. Bulletin of the British Museum (Natural History). 104 COCKS & RONG. Fig. 48 Leptellina (Leptellina) tennesseensis Ulrich & Cooper, 1936, from Lenoir Formation (Liandeilo), quarter mile west of Friendsville, Tennessee, USA, interior of brachial valve, based on BB 1228, x 5. 1952 Benignites Havh'5ek: 13 1965 Leptellina Williams: H376 1965 Merciella Williams: H376 pars 1967 Leptellina Havli'cek: 27 pars 1976 Urbimena Havli'cek: 367 1976 Benignites Havli'cek: 368 1983 Qianjiangella Liang in Liu et al.: 274 '\ 1984 Leptellina (Mabella) Klenina: 69 Type SPECIES. Leptellina tennes
. Bulletin of the British Museum (Natural History). 104 COCKS & RONG. Fig. 48 Leptellina (Leptellina) tennesseensis Ulrich & Cooper, 1936, from Lenoir Formation (Liandeilo), quarter mile west of Friendsville, Tennessee, USA, interior of brachial valve, based on BB 1228, x 5. 1952 Benignites Havh'5ek: 13 1965 Leptellina Williams: H376 1965 Merciella Williams: H376 pars 1967 Leptellina Havli'cek: 27 pars 1976 Urbimena Havli'cek: 367 1976 Benignites Havli'cek: 368 1983 Qianjiangella Liang in Liu et al.: 274 '\ 1984 Leptellina (Mabella) Klenina: 69 Type SPECIES. Leptellina tennesseensis Ulrich & Cooper, 1936. Type species of Benignites is Strophomena primula Barrande, 1879; of Mabella is Leptellina (Mabella) semiovalis Klenina, 1984; of Qianjiangella is Q. quianjiangensis Liang, 1983 and of Urbimena is U. mareki Havli'cek, 1976. Diagnosis. Normal convexity. With platform. Pedicle valve muscle field small (usually less than quarter valve length). Thin central ridge to cardinal process with lateral compo- nents less prominent (only thin central process projecting posteriorly from hinge line, and even this is sometimes entirely anterior to the hinge line). Remarks. The muscle field in the pedicle valve shows some variation. In most species, including the type species, it is small and does not extend more than a quarter of the valve length, and the adductor scars are usually open anteriorly. However, in L. (Merciella) the adductor scars are enclosed anteriorly by the diductor scars. This genus was very common in Llanvirn to Ashgill times, and in many cases dominated the community in which it occurred. Further research might recognize more features worthy of subgeneric recognition, but we have been unable to recognize any (apart from those of Merciella), and so we group here all the species hitherto attributed to Leptellina, Benignites, Mabella, Qianjiangella and Urbimena into a single undivided Leptellina (Leptellina). Benignites is said by Havli'cek (
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