41 8 MONOTOCARDIA — TAENIOGLOSSA chap. 



Fam. 34. Vermetidae. — 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 

 corneous, circular, nucleus central. Carbo- 

 niferous . Principal genera: Vermetus; 



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

 or series of holes, runs along a considerable 

 part of the shell, operculum with outer face 

 Fig. 276. -Develop- spiral, elevated. 



showing the gradual Fam. 35. Stromhidae. — Foot uarrow, arched, 

 formation of septa; metapodium PTcatly produced, snout longr, eye 



€L £IjT)PX ' at) J5T)PT- C5«/J. ■' 0'»/ 



ture; ss, first sep- peduncles long, thick, eyes elaborate, siphon 

 turn ; s's', second short, penis prominent, bifurcate ; central tooth 



septum. (After de .^, ^ t • i <- i -i- 



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

 formofC'.e&wmewm slender, edpfc 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), 

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

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



Fam. 36. Chenopodidae (^—Aporrhaidae). — Foot flat; lateral 

 and marginal teeth not denticulate ; shell resembling that of 

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



. Genera: Ohenopus (^ = Aporrhais, Diastema, Malaptera, 



Harpagodes, Alaria (last four from Secondary strata). 



Fam. 37. Struthiolariidae. — Radula allied to that of AS'^rowJws, 

 marginals occasionally multiplied ; shell buccinoid, very solid, 

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



nucleus terminal. Tertiary . Single genus, Strutliiolaria 



(subg., Perissodonta, marginal teeth multiplied). 



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

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

 lateral 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 



t 



