6 



type. The Californian land shells seem very difficult to understand on account 

 of their varia'5 on. Although this shell bears little resemblance to Calif or niensis, 

 Lea, as fig. in Tr. Am. Ph. Soc, vi., pi. xxiii., f. 19, there is a gradual blenditig 

 of the two. For some of the links in the connecting chain, see the fig. Terr. 

 Moll, iii, vi. a, Reeve, Con. Icon. 661, and Chemn. Ed. 2, pi. Ivii. fig. 14, 15. The 

 last resembles arrosa, var. ,3 very much. This connecting chain of resemblance 

 is also carried by specimens in my cabinet to D/ipeiiihuarsi, Desh. Future 

 research will alone enable us to draw the correct divisions of the species. 



Helix (Polygyra) tholus. Testa solidiuscula, albida, nitens, costis obliquis 

 notata; spira rotundata, elevatiuscula, obtusa, tholiformis ; sutura valde im- 

 pressa, anfr. 7, convexiusculi, superi magis planulati, ultimus ad apertu- 

 ram descendens, obtuse carinatus, carina peristoma non attingens, post 

 perist. caualiculatus ; infra carinam costae minus distinctae ; basis plana, um- 

 bilicus latus, perspectivus, anfractus canaliculatos monstrans, quorum 2J per- 

 spicue alii obscure videntur; apertura perobliqua, ab axe remota; perist. album, 

 semicirculare, latum, incrassatum, margine basali reflexiusculo, dentibus duobus 

 sinu rotundato disjunctis armatum; plica parietalis acuta, in medio aperturae 

 projecta, margines peristomatis vix connectens. Diam. maj. 11; min. 9 ; alt. 

 4 mill. 



Habitare in Texas suspicor, sed incertus sum. Specimen unicum vidi in coll. 

 Bland conservatum. 



Shell rather solid, white, shining, ribbed above, smoother below; spire obtuse, 

 little elevated, rounded ; whorls seven, convex, the uppe^ ones more flattened, 

 the last bluntly carinated ; carina not reaching the peristome; base parallel to 

 the suture ; umbilicus broad, half the larger diameter of the shell, showing 

 two and a half deeply grooved whorls plainly, the others rapidly retreating 

 towards the apex ; aperture very oblique, semicircular, removed from the axis 

 of the shell, bordered with a scarcely reflected, white, heavy rim, grooved 

 behind, and armed with two stout teeth near the basal extremity, broadly 

 reflected at the junction with the body whorl ; on the parietal wall of the aper- 

 ture is a white fold, hardly connecting the extremities of the lip, and projecting 

 across the aperture into an acute point. 



The aperture of this curious shell resembles that of B.. faiiffiata, Say. It is 

 readily distinguished from that and all other described species by the umbili- 

 cus, broad at the commencement, and rapidly narrowing beyond the second 

 whorl, with the peculiar groove visible in all the whorls of the umbilicus, of the 

 same character as that noticed by Say in auriculata, though deeper. 



The name is derived from the resemblance of the slightly raised, rounded 

 spire to a low dome. 



Helix kopnodes. Testa depresso-globosa, corrugata, subtus laevigata; spira 

 hrevis, depressa ; sutura mediocris ; anfr. quinque, rapide accrescentes, ultimus 

 permagnus, ventricosus, interdum lineis volventibus crassis notata; apertura 

 magna, rotundata; perist. simplex, acutum, marginibus approximatis, callo levi, 

 brunneo conjunctis ; ad umbilicum parvum et profundum reflexiusculuir. 

 Diam. maj. 35; min. 28; alt. 13 mill. 



Habitat in Alabama, (C. S. Hale !) 



Forsan forma monstruorsa H. fuliginosce, Binney, sed diflfert speciminibus 

 meridionalibus colore, testa majori, solidiori, magis globosa; umbilico angus- 

 tiori; apertura majori, magis rotundata, spira magis elevata; et lineis volventi- 

 bus. Varietates alligantes non exstant. 



Figura Reeveana, Con. Icon. No. 672. Etsi minus globosa, afBnis paritur sed 

 minute costellato-striata dicitur. 



Shell depressed-globose, wrinkled, below smooth; spire short, depressed; 

 suture moderate ; whorls five, rapidly increasing, the last very ventricose and 

 large, sometimes marked with coarse revolving lines; aperture large, round, 

 lip simple, acute, ends approached, joined by a slight deposition of brownish 

 callus over the parietal wail, reflected at the small and deep umbilicus. 



It is a much larger and more globose shell than H. fuUyinoso, Binney, with a 



[October, 



