4i8 



MONOTOCARDIA TAENIOGLOSSA 



Fam. 34. Vermetidac. — Visceral sac greatly produced, 

 irregularly spiral, no copulatory organs (radula, Fig. 126, p. 

 223), shell tubular, irregularly coiled, last 

 whorls often free, aperture circular; operculum 

 ccjrneous, circular, nucleus central. Carbo- 

 niferous . Principal genera : Vermctus ; 



Fam. 35. Stromhidae. — Foot narrow, arched, 

 nietapodium greatly produced, snout long, eye 

 peduncles long, thick, eyes elaborate, siphon 

 sliort, penis prominent, bifurcate; central tooth 



Siliquaria (Fig. 153, p. 248), a long fissure, 

 or series of holes, runs along a considerable 

 part of the shell, operculum with outer face 

 Fifi. 276. — Deveioji- spiral, elevated. 



nieiit of Coeaim : A, 

 showing the gradual 

 formation of septa ; 

 ((, apex ; ap, aper- 

 ture ; ss, first sep- 

 tum ; s's', second 

 septum. (After de • i p i -p 



Foiin.) B, adult With strong median cusp, marginals laicilorm, 

 iovm oi a eburnetivi glender, edge more or less denticulate; shell 



Ad., Panama, x 10. ,., '. ^ . , .. ^^ \■^ 



solid, spire conical, outer lip generally dilated 

 into wings or digitations, channelled before and behind, a labial 

 sinus at the base, distinct from the anterior canal; operculum small 



for the aperture, corneous, claw-shaped, edge notched. Lias . 



Genera: Strombus (Fig. 99, p. 200); Pereiraea (Miocene), 

 Pteroceras (Fig. 277; digitations of the outer lip very strong), 

 Postellaria (spire produced, anterior canal very long), Bimella, 

 Pterodonta, Terebellum (base of shell truncate, spire short). 



Fam. 36. Chenopodidae {=: A2wrrhaidae). — Foot flat; lateral 

 and marginal teeth not denticulate ; shell resembling that of 

 Strombus, outer lip dilated, wing-like, no labial sinus. Jurassic 



. Genera : Chenojms ( = A^wrrhais), Diastema, Mala^ptera, 



Harpagodes, Alaria (last four from Secondary strata). 



Fam. 3 7. Struthiolariidae. — Eadula allied to that of Strombus, 

 marginals occasionally multiplied ; shell buccinoid, very solid, 

 outer lip thickened, canal short, operculum claw-shaped, notched, 



nucleus terminal. Tertiary -. Single genus, Struthiolaria 



(subg., Perissodonta, marginal teeth multiplied). 



Fam. 38. Cypraeidae. — Mantle with two large lateral lobes 

 reflected and meeting over the shell, siphon small ; central and 

 lat(u-al teeth bluntly tricuspid or multicuspid, laterals fairly 

 broad, edges cusped or finely pectinate ; shell polished, solid, 

 spire generally concealed in the adult or overlaid with enamel, 

 aperture straight, narrow, nearly as long as the shell, toothed at 



