TUE NAUTILUS. 93 



Unio vestitus H(Midf. 



Described by R. P. Ileiide in 1883 in Condi. Fluv. Nankinjr, 



VIII, phite Iviii, fi;,'. 112, and plate lix, fig. 11 G. 



Mr. Sim|)Son very properly cbanged the specific name vestitus, 

 it having, as he remarlis, been preoccupied by Lea. Mr. Simpson 

 erred, however, in thinking that the two figures represented different 

 species, so diverse as to be phiced in different genera, i. e.. fig. 112 

 a Quadrula, aiid fig. 116 a Schistudesmus. Tlie two figures are, as 

 Heude says, one species. Mr. Simpson's new name for fig. 112, 

 Quadndd ovnta^w'xW iiave precedence, and the shell being properly a 

 Schistodesimis will therefore be called Scliistndesvms ovatiis Simpson, 

 and Mr. Simpson's name for fig. IIG, Schistodesinus spiiwsus, becomes 

 a synonym. 



Unio compressus Heude. 



Conch. Fluv. Nank., Ill, 1877, plate xxiv, fig. 52. 



This specific name, being preoccupied, was changed by Mr. Simp- 

 son and called by him Ptychorynchus incertus Simpson, and the Unio 

 murinus of Hende placed as a synonym, although the murinus had 

 been published some seventeen years previousl}'. This slip, how- 

 ever, was corrected in the "Errata" by Mr. Simpson by placing 

 WMri'nJW as the specific name, and incerttis Simpson becomes obsolete. 

 But Mr. Simpson evidently overlooked the fact that this name ot 

 compressus liad been subsequently abandoned by Heude himself, and 

 that its natural affinities had been pointed out by Heude not once 

 but twice. So far from being so closely allied to the Ptychorynchus 

 murinus Heude, it is not even entitled to beinir placed in the same 

 genus at all, but is very close to the Nodidaria douglusics Gr.'iy. In 

 fact Heude in the first mention of the species (fig. .52, plate xxiv) 

 calls attention to its kinship to the Unio scniplns Desliayes, which he 

 figures on the same plate, and which figure Mr. Simpson places as a 

 synonym of doughtsicE. Afterwards Heude abandoned the name 

 compressus and >ul)Siituted the name snhpressns (Conch. Fluv. Nank., 



IX, 1883, pi. Ixv — " Bemarks opposite "), which he then places as a 

 variety q\' dough i sice Gray. 



(This whole double plate of douglnsicE Gray and its varieties, as 

 given by Heude, is omitted by Mr. Simpson in the references under 

 Unio douglasiae, page 808, of the Synopsis.) 



This shell, however, is a good species, allied to douglasicB, but 



