INVERTEBRATE PALAEONTOLOGY. 381 



PUuroloma, Lamarck (1799), Prodr., 73; and (1801) Syst., 84; also (1809), Phil. Zoiil.,* * ; and 

 (1822), Hist., VII, 90.— Cuvier (1817), Regne An., II, 442 (as a subgenus under Fusus); 

 and (1830) ib. (6d. 2e), 111,387 i :is :i Biibgenus under Murexi).— Blainv. (1824), Diet. Sci. 

 Nat., XXXII, 196; aud (1825) Malac., 394; also (1820), Diet. Sci. Nat., XLI, :!-■<.— 

 Swainson (1840), Malac., 314.— Gray (1842), Sjuod. Brit. Mas., 89.— Hinds (1844), 

 Voy. Sulph., Zool., 15.— D'Orbigny (1850), Prodr. do Pal., II, 230.— Shumard (1861), 

 Proceed. Host. Soc. Nat. Hist., 197.— Stoliczka (1868), Palwont. Iudica, II, 67.— Gabb, 

 (1869), Pala'ont. Cal., II, 5; and of many others. 



Pleurolomarius, Dum. (1806), Zoiil. An., 340. 



Turricda, Sebum. (1817), Essai, 217 (not Klein, 1753 ; Humph., 1797 ; Fab., 1822 ; or Beck, 1837). 



Pkurotomus, Montf. (1810), Conch. Syst., II, 534. 



Pleurotomites, Kriig. (1823), Urw., II, 425. 



Surcula, H. and A. Adams (1853), Genera Recent Moll., I, 88 (as a subgenus under Tunis). — 

 Meek (1864), Smithsonian Check-List N. Am. Cret. Fossils, 22 (as a subgenus under 

 Turns). — Conrad (1865), Am. Jour. Conch., I, 18; and (1866) Smithsonian Check-List 

 N. Am. Eoc. Shells, 18 (as a genus). — Gabb (1869), Palseont. Cal., II, 150 (as a genus). 



Genota, H. aud A. Adams (1853), Geo. Eecent Moll., I, 88 (as a subgenus under Turrit). 



Surculites, Conrad (1865), Am. Jour. Conch., I, 213 (as a subgenus under Surcula).— Gabb (1869), 

 Palieont. Cal., II, 150. 



Etijm. — Tunis, a tower. 



Type. — Murex Babylonius, Linnaeus. 



Shell fusiform ; spire more or less produced, turreted, not mammillate 

 at the apex ; volutions convex, sometimes angular, and often nodose or 

 costate ; last one narrowed anteriorly into a more or less produced, straight, 

 or slightly bent canal ; columella smooth and rounded ; inner lip moderately 

 developed, or sometimes obsolete ; outer lip thin, not indexed, but provided 

 with a more or less deep slit, or sinus, posteriorly. 



Animal, in the existing species, with eyes at the outer bases of the 

 tentacles, and provided with an ovate, pointed operculum, with an apical 

 nucleus. 



The foregoing diagnosis is drawn up so as to include four sections, or 

 subgenera, distinguished from each other as follows : 



1. turris, Bolten (typical). 



Shell with spire elevated, and canal generally produced and 

 straight ; inner lip moderate ; outer lip with a deep slit near the 

 suture. — (Type as already stated.) 



2. surcula, H. and A. Adams (=. Turricula, Schum. ; not of others). 



Shell with spire and canal generally rather produced, the latter 

 slightly bent ; inner lip obsolete ; outer lip more or less sinuous pos- 

 teriorly. — ( T. nodi/era, Lam.) 



