64 THE NAUTILU3. 



the figures it is impoBBible to definitely ascertain to what genun 

 either this sjjecies or H. evami M. & H., from the same locality 

 and formation, belong, but whatever the genuB, the name occi- 

 dentalis should not be used. As to H. evansi, which is based 

 upon poor and probably immature material, we agree with Dr. 

 Pilsbry, who writes: "It is better to leave uncertain shells of 

 this kind in ^ Helix, ^ as uncertain generic reference may lead 

 some one to baseless deductions. Paleontology is full of the 

 most reckless generic references." He also calls attention to 

 the fact that H. occidentalk Recluz, i«« now considered a Hygromia, 

 ranking as a variety, but that does not restore Meek and Hay- 

 den's first name for their species. 



Planorbis vetulus Meek and Hay den, was described from the 

 Tertiary of South Dakota in 1860 (Proc. Acad. Nat. Sci., Phila., 

 XII, pp. 175, 431). In 1864 (Smithsonian Check-list of In- 

 vertebrate Fossils of North America — Miocene, p. 13) Meek 

 called it P. vetmtus, since which time the latter name has been 

 almost universally used, though no reason was given for the 

 change. The change was likely inadvertent, though possibly 

 deliberate, as authors in those days did not always hesitate 

 about changing names to suit their own notions. Unless vetu- 

 Im is preoccupied, of which I have found no evidence, it must 

 stand as the name for this species. 



A somewhat similar case is that of Campeloma vetula Meek 

 and Hayden, which was first described as Paludina vetula, and 

 afterwards cited by the same authors as P. vetusta and changed 

 to Vivipara vetmta, but fortunately in that case the original name 

 has been used by most subsequent authors, though White 

 (U. S. Geol. Surv., Bull. 128, p. 77) made the curious mistake 

 of supposing that V. vetmta and C. vetula are distinct species. 



Limmea tenuicosta Meek and Hayden, Eocene, near Fort Union. 

 N. D., was described in 1856 (Proc. Acad. Nat. Sci., Phila., 

 VIII, p. 119). In 1860 the same authors (Proc. Acad. Nat. 

 Sci., Phila., XII, p. 431) cited the original description but 

 spelled the name tenuicosiata, without offering any reason, and 

 the majority of subsequent writers have used the latter name, 

 instead of the former. 



