FAUNA OF OETHAULAX PUGKAX ZONE. 113 



Family HELICINIDAE. 



Genus HELICINA Lamarck. 



Helicina Lamarck, Pr<xlrome, 1799, p. 76 (no species mentioned) ; Syst 

 des Anim. s. Vert. 1801, p. 94. Type, Hciiciini ncritcila Lamarck after 

 Lister, pi. 62, fig. 59 (Barbados) ; not of Roissy. Hist. Gen. des Moll., 

 vol. 5, 1806, p. 275. pi. 54, fig. 1 ( = UnibonUim Link). — Pfeiffeb, 

 Pneumop. Viv., 1852, pp. 338, 362. 



This genus was founded by Lamarffk on a figure of a snail from 

 Barbados given by Lister as above cited, and an unquestionable 

 member of the genus as generally understood. However, Roissy, 

 in adopting the genus a few years later, made the mistake of figuring 

 a species of V7rbboniu7n {RoteUa Lamarck) as an example of La- 

 marck's genus. This error misled Gray and some others, who 

 probably did not take the trouble to look up the original figure in 

 Lister, into regarding the type of Helicina as a marine shell. 



HELICINA BALLISTA Dall. 

 Plate 15, figs. 9, 11. 



Helicina haUista Dall, Trans. Wagner Inst., vol. 3, pt. 1. p. 3, pi. 1, figs. 

 2, 2a, 1890. 



Tampa silex beds at Ballast Point and in the overlying Tampa 

 limestone with Orhitolites; and in rock of the same age at Six-Mile 

 Eun, near Orient Station, east of Tampa City ; all collectors. U. S. 

 Nat. Mus. No. 111939. 



HELICINA BALLISTA var. TAMPAE DaU. 



Helclna balUsta var. tmwpae Dall, Trans. Wagner Inst., vol. 3, pt. 1, 

 p. 4, 1890. 

 With the last, and nearly as abundant. U. S. Nat. Mus. No. 

 111943. 



. This is similar to the typical form and has the same number of 

 whorls, but is generally smooth and slightly flatter on the spire 

 beside being constantly smaller. If we had it in its original condi- 

 tion, probably there might be specific differences of color which 

 are lost in the fossil state, but as it stands the safer plan seems to 

 be to regard it as a variety of the larger shell with which it is asso- 

 ciated. 



HELICINA POSTI, new species. 



Plate 5, fig. 7. 



Shell in form much resembling H. haUista var. tamfae, but larger, 

 proportionately more' depressed, with a less thickened peristome, per- 



54907°— Bull. 90—15 8 



