202 LAND AND FRESH-WATER SHELLS OF N. A. [PART I. 



There can, I believe, be no doubt that the shell under con- 

 sideration is what Mr. Say described as alternatus. This 

 description is given above, and a copy (Fig. 347) of a colored 

 drawing by Mrs. Say, under which is written, in Mr. Say's 

 hand, " Bulimus alternatus, Mexico, Wm. Maclure." 



The species was known to Dr. Binney and figured in the Ter- 

 restrial Mollusks, but as a variety of B. dealbatiis. Plate 51b, 

 and the upper and lower figures of plate 51a certainly represent 

 the species. The central figures of plate 51 a represent a variety 

 of B. dealbatus (q. v.), as does also, I should judge, figure 2 of 

 plate 51,* though the last may be B. schiedeanus. 



In vol. 4 of Terrestrial Mollusks I took the same view of Bid. 

 alternatus as at present, having the original figure of Mr. Say to 

 assist in determining the species (pi. 80, f. 3). I figured (pi. 80, 

 f. 1) a specimen on which a dark brown color is but slig^htly 

 broken by white upon the upper whirls. Fig. 15 of the same 

 plate should be also referred to B. altefnatus. On account of the 

 lesser development of the columellar fold I erroneously referred 

 it to B. schiedeanus. On p. 128 I repeated Pfeiffer's description 

 of Bulimus mariae. I had seen no specimen, and admitted the 

 species only temporarily, observing that it must be nearly allied, 

 if not identical with B. alternatus. Since that time I have re- 

 ceived authentic specimens, and have learnt that Bui. marise was 

 described from specimens similar to those I have considered as 

 Bui. alternatus. While preparing the fourth volume of the 

 Terrestrial Mollusks for publication I sent to Dr. Pfeiffer for 

 identification specimens like those figured on plate 51b. He 

 returned them wnth the name B. hinneyanus. This will account 

 for the use of that name on p. 128. I have subsequently learnt 

 that, deciding the specimens sent to be a variety of B. marise, he 

 applied the name B. hinneyanus to quite another species (Proc. 

 Zool. Soc. 1858, pi. xlii, f. 4). 



Pfeiffer gives Say's description of B. alternatus as a species 

 unknown to him. It is not mentioned by other authors. 



Bulimus marise, Albers, is referred to alternatus from the 

 description, given below, of Albers and Pfeiffer,'' from the figure 



1 In the explanation of the plates in vol. Ill, Dr. Gould refers plate 51 b 

 to Bui. schiedeanus, pi. 51a to lactarius, and fig. 2 of 51 to alteryiatus. 



2 Plate 51b of Terr. Moll, is referred by Pfeiffer to a form of B. maria, 

 pi. 51a to lactarius, which he says may be alternatus, and pi. 50, fig. 2 to 

 schicilcanus. 



