112 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.xxii. 



deep, reaching to or beyond the beaks, posterior adductor scar rounded, 

 the scar of the sinus coalesceut ventrally with the pallial Une; situs 

 estuarine or marine. 



Section MESOPLEURA Conrad, 1867. 



Type. — Solen dlvisus Spengler. 



Valves arcuate, not constricted, but with a more or less perfectly 

 developed clavicular rib extending ventrally from the submedian beaks, 

 otherwise as in Tagelus. 



Gray in 1854 included species of Glunaculum uxxdev NovacuUna as well 

 as some species of true Tagelus like T. domhuji. I have not been able 

 to examine all the described species, but Solen constrictus Lamarck, cer- 

 tainly, and probably 8. inequalis and S. complanatus Sowerby, belong 

 to Clunacidum. 



TAGELUS POEYI, new species. 



Shell resembling a young T. gibbus, but with more equal and evenly 

 rounded ends, the beaks median, the teeth slender, long, but quite 

 small, the nymphs for the ligament shorter and more central, the whole 

 of the ventral side of the pallial sinus coalescent with the pallial line. 

 Shell white, covered with a pale ashy gray, debiscent epidermis; the 

 anterior dorsal margin slightly decurrent. Length, 50 mm.; altitude, 

 18 mm.; diameter, 11.5 mm. 



Types.— ^o. 27425, TJ.S.N.M., from Cuba (Poey); also from mouth 

 of Old Eiver, Belize (Stanton); beach at Greytown, Nicaragua (Dall); 

 and Eio Grande do Sul, Brazil (Ihering). 



This species can be instantly distinguished from T. gibbus by the dif- 

 ferent form of the pallial sinus and the different position of the beaks. 

 It does not appear to attain more than half the size of the full grown 

 T. gibbus. 



Specimens of T. gibbus collected at Matagorda Bay, Texas, by Sing- 

 ley, of a light but distinct yellow color, are in the national collection, 

 and more recently Hon. J. D. Mitchell has sent specimens, of which he 

 has several in his collection, of a decided pink color, from the same 

 vicinity. Both form a decided contrast to the white or slightly ferru- 

 ginous tint of the average specimens of this species. 



