NO. 5 RHYNCHONELLOID BRACHIOPODS — COOPER 29 



extend anteriorly, generally following the outer slope of the median 

 trough formed by the fold. The vascula media branch at midvalve and 

 the branches form a course similar to those of the opposite valve. 



The genus Neohemithyris as defined by Yabe and Hatai in 1934 is 

 identical to Basiliola. The authors of this genus emphasize the con- 

 junct deltidial plates and the nature of the foramen. Specimens of 

 Rhynchonella lucida Gould, type species of Neohemithyris, have been 

 compared with B. bcecheri and proved generically identical. In fact 

 the Japanese species suggests immature B. beecheri. 



Specimens (U.S.N.M. 499321) from Vanua Mbalavu, Lau, Fiji, 

 referred by Ladd and Hoffmeister (1945, pp. 329-330) to Neohemi- 

 thyris lucida, are young forms having the characters of Basiliola. The 

 genus Basiliola thus proves to have a far wider range in the Pacific 

 than hitherto believed. 



BASILIOLA ELONGATA Cooper, new species 



Plate 14, C 



Not Basiliola pompholyx Dall, Proc. U. S. Nat. Mus., vol. 57, p. 292, 1920 

 (U.S.N.M. 235844 and 300266). 



Shell thin, of about medium size, elongate oval in outline ; greatest 

 width anterior to the middle ; beak acute, forming an angle of about 

 8o°. Anterior margin nearly straight ; anterior commissure moderately 

 uniplicate; valves subequal in depth, the brachial valve being slightly 

 deeper than the other; surface marked only by concentric lines of 

 growth. 



Pedicle valve gently convex in lateral profile, with the maximum 

 convexity in the posterior half; anterior profile broadly but gently 

 convex; umbonal region moderately and narrowly swollen and with 

 steep lateral slopes ; sulcus originating just anterior to the middle, 

 broad and shallow; tongue short and abruptly truncated; flanks 

 gently inflated and with gentle slopes. Foramen elongate-oval, fairly 

 large; deltidial plates conjunct and with a marked lip on the anterior 

 side of the foramen. 



Brachial valve fairly evenly and moderately convex in lateral pro- 

 file ; strongly convex in anterior profile ; umbonal and median regions 

 inflated ; umbonal slopes steep ; fold originating at about midvalve, in 

 the anterior third slightly elevated above the surrounding flanks which 

 are moderately swollen and steep sided. 



Pedicle valve interior with small teeth and short, inconspicuous 

 dental plates ; diductor field moderately large, flabellate not strongly 

 inserted ; genital areas narrowly crescentic ; pallial marks not strongly 



