POTAMIDES (PTYCHOPOTAMIDBS) TRTCTNCTUS. Ill 



ridges which reach the sutures and the base of the shell, and by numerous 

 inconspicuous lines of growth; suture fairly deep; spire regularly tapering 

 upwards to a sharp point; mouth ovate, angulated above; outer lip thin, gently 

 curved and slightly expanded ; folds on the columella well marked. 



Dimensions. — L. 10 mm. B. 5 mm. 



Distribution. — Not known living. 



Fossil: Scaldisien : Antwerp. 



Remarks. — When making a rapid and as I hoped a preliminary examination of 

 the interesting collection of Belgian fossils accumulated by M. van de Wouwer of 

 Antwerp, he was good enough to allow me to select several specimens of what I 

 believe to be an undescribed form of Admete allied to J. gracilenta but sufficiently 

 distinct to be regarded as a new species. I am afraid to think what my good 

 friend may have suffered during the occupation of his country by its pitiless foes. 

 I can only dedicate this charming little shell to him in grateful recognition of his 

 zeal as a student of the Antwerp Crag and of the kind assistance he so willingly 

 rendered me during my visits to Antwerp. I have met with no trace of this form 

 in the Waltonian deposits, but it may turn up in them hereafter. In sculpture, 

 though not altogether in form, it resembles a species described by Mr. Friele as 

 new under the name of A. inflata {op. cit., pt. ii, p. 25, pi. viii, fig. 33). 



Genus POTAMIDES, Brongniart, 1810. 

 Sub-genus PTYCHOPOT AMIDES, Sacco, 1895. 

 Potamides (Ptychopotamides) tricinctus (Brocchi). Plate XL, figs. 23—25. 



1814. Murex tricinctus, Brocchi, Conch, foss. subap., vol. ii, p. 446, pi. ix, fig. 23. 

 1842-72. Cerithium punctatum, S. V. Wood, Ann. Mag. Nat. Hist. [1], vol. ix, p. 537, 1842; C. tri- 

 cinctum, Mon. Crag Moll, pt. i, p. 69, 1848 ; 1st Suppl., pt. i, p. 51, pi. iii, fig. 19, 1872. 



1870. Cerithium tricinctum, S. V. Wood, Jr., and F. W. Harrner, Eep. Brit. Assoc. (Liverpool), 

 Trans. Sect., p. 90. 



1871. Cerithium tricinctum, Jeffreys in Prestwich, Quart. Journ. G-eol. Soc, vol. xxvii, p. 487. 



1872. Cerithium tricinctum, A. and R. Bell, Proc. Gteol. Assoc, vol. ii, pp. 203, 209. 



1874-92. Cerithium tricinctum, Van den Broeck, Ann. Soc. Roy. Malac. Belg., vol. ix, pp. 272, 280, 

 285, 1874; vol. xiv, p. 76, 1879 ; vol. xvii, p. 204, 1882 ; Bull. Soc. Beige Ge'ol., vol. vi (Memoires), 

 p. 123; C. (Potamides) tricinctum, p. 133, 1892. 



1875. Cerithium tricinctum, Seguenza, Boll. R. Com. Geol. Ital., vol. vi, p. 344, no. 418. 



1878. Potamides tricinctum, de Stefaui e Pantanelli, Bull. Soc. Malac. Ital., vol. iv, p. 159. 



1881. Cerithium tricinctum, Njst, Conch. Terr. Tert. Belg., p. 79, pi. vi, fig. 10. 



1890. Cerithium tricinctum, C. Reid, Plioc. Dep. Brit., pp. 53, 241. 



1890-5. Potamides tricinctus, Sacco, Boll. Soc. Geol. Ital., vol. ix, p. 190, no. 2125, 1890 ; P. (Ptycho- 

 potamides) tricinctus and vars., Moll. Terr. Terz. Piem., pt. xvii, p. 44, pi. iii, fig. 8, 1895. 



