130 THE NAUTILUS. 



On the otlier hand, the A710. gibbosa Say, is a rather rare shell 

 and geiiernlly misnamed. It is remarkable lor the great ])roluberance 

 of its beaks and umbos, and the swelling of the umbos continues 

 (with tlie growtli of the sliell) downwards and backwards. Tliis 

 peculiarity gained for the S|)ecies its name. A. gibbosa belongs to 

 the group of cataracta Say, having a double row of undulations on 

 its beaks, and it is really very doubtfully distinct from this variable 

 species. 



I\Ir. Lea, having obtained specimens of this shell, in which the 

 umbo to post-basal swelling was not very pronounced, he made a 

 new species, which he called A. dariensis. The gibbosa being a rare 

 shell, as such its identity has well-nigh been lost. For example, a 

 typical specimen, so-called by the late G. W. Tryon, was labelled as 

 A. darieitsis by Mr. Simpson, and the Anodovia daritnsis figured by 

 Sowerby is a gibbosa. 80 also is the gibbosa figured by Sowerby 

 (or Reeve) in plate XI, fig. 23. (This figure is not mentioned by 

 Ml'. Sinipson). The shell is well figured also by Clessin, jtlate 

 XVIII, tigs. 3 and 4, under its proper nsime. Mr. Simpson refers 

 these figures to gibbosa Say, correctly. But he also refers (as this 

 species) to Sowerby 's covperiana, and especially to Clessin, plate 

 50, Hgs. 3 and 4. 



Evidei'ily Mr. Simpson did not compare these figures with one 

 another, for that Clessin's plate oO figures 3 and 4, and plate 18, fig. 

 3 and 4 re[)resent two entirely diverse species would be apparent to 

 the veriest tyro. Couperiana, Lea (witii its variety dunlapiana) 

 then is to be recognized as a good species, and gibbosa. Say is also 

 a good species with dariensis as a synonym, or at best a variety. 



POLYGYRA ALBOLABRIS ALLENI WETH , AND OTHER MISSOURI 



HELICES. 



BY F. A. SAMPSON. 



Years ago when collecting shells at Eureka Springs, Arkansas, 

 Charles C. Allen, then of that place, later of Florida, became inter- 

 ested in conchology, and a variety of P. albolabris found there was 

 named for him by Prof. Wetherby, and it has since been decided 

 that all of the P. albolabris west of the Mississippi and south of Iowa 

 are of that variety. 



