98 PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 



fossil species. The latter seem to differ from the sheila of living species 

 of Ano)iiia only in the lack of development in the under valve of the 

 pearly layer, and the excessive development of the prismatic layer. 



Pyrgulifeba Meel- and Paramelania Smith. 



There occurs somewhat abundantly in the Bear Kiver Laramie beds 

 of Southwestern Wyoming and the adjacent parts of Utah a shell which 

 Mv. ]\Ieek first referred to Melania, but to which he afterward gave the 

 new generic nameotPj/zY/^/i/era, describing it under the name of Pyrgu- 

 Ufera humrom.* It is illustrated on Plate III, figs. 10, U, aud 12. Meek 

 ])laced this shell among the Ceriphasiida? or American Melaniaus, but 

 as it seems to differ quite as widely from the typical forms of that fam- 

 ily as it does from the true Melaniaus, I have placed it i)rovisionalIy 

 with the latter family. It is the only known species of the genus which 

 has beeu i)roposed to receive it, either fossil or liviug, if we except the 

 two living forms which were described by ]\Ir. Edgar A. Smith from Lake 

 Tauganyiki, in Africa,t under the new sub-generic name Paramelania. 

 ]\Ir. Smith gave these two forms the names P. damoni aud P. cras-si- 

 </ranulata, respectively. Copies of his figures of both these forms are 

 given on Plate III for comparison. 



ParameJania, as represented both by thesx? figures aud Mr. Smith's 

 (^description, seems to be exactly equivalent with Pyrgnlifera Meek. It 

 jjts ttrue that we -can never know whether the animal of the latter was 

 genferically the same as that of the former, and the wide chronological 

 and grgographical separation of the fossil and liviug forms is presumptive 

 .evideu<yi€ against their generic identity. But if we are justified iii estab- 

 lishing- geszera upon shells alone, as we must do in paleontology, we are 

 entjtkd to iiold them as against anything except direct proof of error. 



EXPLANATION OF PLATE III 



Unio CLINOPISTIIUS (sp.UOV.). 



^Fig. 1.— -Left vside view ; natural size. 

 FijLf. 2. — Dorsal view of the same example, 



Anomia MiCRONKMA Meek. 



Fig. 3.— Yiew of the under valve, showing the byssal plug. 

 Fig. 4. — Exterior view of an upper valve. 



Fig. 5. — Similar view of aaiother example, showing coarser radiating lines. 

 Fig. 6.— Interior view of a very large upper valve, showing muscular scars aud 

 process beneath the umbo. All of natural size. 



Campeloma pkoducta (sp. nov.). 



Fig. 7. — Lateral view of type specimen ; natural size. 



Fig. 8. — Opposite .view of the same. 



Fig. 9. — Lateral view of a more robust example. 



* For diagnosis of this genus, and description and figures of the species, see U. S. * 

 (Gcol. Sur. 40th Parallel, vol. iv, p. 146, pi. 17, fig. 19. 

 tSee Proc. Zool. Soc. Lend, for May, Ibdl, pp. .558-.5C1. 



