THE NAUTILUS. 93 



UNIO VESTITUS Heude. 



Described by R. P. Heude in 1883 in Conch. Fluv. Nanking, 



VIII, plate Iviii, fig. 112, and plate lix, fig. 11G. 



Mr. Simpson very properly changed the specific name vestitus, 

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

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

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

 a Quadrula, and fig. 116 a Schistodesmus. The two figures are, as 

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

 Quadrula ovata, will have precedence, and the shell being properly a 

 Schislodesnms will therefore be called Schistodesmus ovotus Simpson, 

 and Mr. Simpson's name for fig. 116, Schistodesmus spinosus, 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 iiicertus Simpson, and the Unio 

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

 been published some seventeen years previously. This slip, how- 

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

 murinus as the specific name, and incertus Simpson becomes obsolete. 

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

 compressus had 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 Ileude, it is not even entitled to being placed in the same 

 genus at all, but is very close to the Nodularia douglasice Gray. In 

 fact Heude in the first mention of the species (fig. ;V2, plate xxiv) 

 calls attention to its kinship to the Unio scnlptits Deshays, which he 

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

 synonym of doitylasice. Afterwards Heude abandoned the name 

 compressus and substituted the name subpressus (Conch. Fluv. Nank., 



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

 variety of douylusia Gray. 



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

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

 Unio douylasiee, page 808, of the Synopsis.) 



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



