602 NORTH AMERICAN INDEX FOSSILS. 



26*. Apertural expansion one of three or more similar ones on same 



whorl forming varices k 7 . 



k/. Varices broad lamellae or rows of spines CLXXIX. Murex. 



k'. Varices rib-like, ending in hollow shoulder spines 62. 



62. Varices of considerable strength, anterior canal covered. 



CLXXX. Typhis. 



...... 62. Varices weak, anterior canal open CLXXXI. Trophon. 



26*, Apertural expansion alone present V. 



V. Expansion a broad and thick lamella, at posterior notch covering 

 spire 63. 



63. With anterior and faint marginal notch... CX LI. Strombus. 



63. Without marginal notch CXXXVII. Aporrhais. 



V. Expansion lobed or digitate 64. 



64. Inner lip expanded and partly covering spire and body 



whorl CXXXVIII. Pugnellus. 



64. Inner lip not expanded, but expansion of outer lip often 



partly covering the spire CXLIA. Plerocera. 



VIII. Shell with spire sunken beneath body whorl, which often completely hides 



the spire 20. 



20. Outer lip enrolled in adult, marginal slit lined by denticulations. 



CXLII. Cyprcea. 



20. Outer lip sharp 27*. 



27*. Apex perforated over the sunken spire m'. 



m 7 . Shell oval, inflated columella smooth CCIII. Bulla. 



xn / . Cylindrical, columella with small plications CCV. Cylichna. 



27*. Apex not perforated n / . 



n'. Cylindrical, aperture extended posteriorly so as to form sharp 

 point above apex, surface smooth or with few spirals. 



CCIV. Volvula. 

 n / . Oval without projecting point, surface with fine spirals. 



CCIJ. Haminea. 



I, Not belonging to the preceding divisions IX. 



IX. Shell twisted or loose-coiled, whorls not in contact 21. 



21. Irregularly twisted, with or without apical coil 28*. 



28*. Tube entire, ornamented by longitudinal striae or smooth. 



CXXII. Vermetus. 



28*. Tube with a slit, or a row of pores CXXIV. Siliquaria. 



21. More or less regular, loose spiral 29*. 



29*. Twisted into corkscrew spiral o / . 



o / . Spiral broad, open ; tube scarcely increasing. 



CXXIII. Laxispira. 

 o / . Spiral long, slender, tube regularly increasing 65. 



65. Tube entire CXXI (internal mold of) Turritella. 



65. Tube with slit or row of holes CXXIV. Siliquai'ia. 



29*. Twisted in single plane, from a part of a volution to several volu- 

 tions not in contact p / . 



p'. Whorls round, unmodified by carina LI. Phanerotinus. 



p'. Whorls with carina or keel on upper side 66. 



66. Carina blunt ; aperture with broad, shallow notch. 



LIX. Eccyliomphalus. 



