4 1 2 MONOTOCARDI A — TAENIOGLOSSA chap. 



Fam. 4. Naricidae. — Tentacles broad in the middle, with 

 sessile eyes at the exterior base, propodium narrow, quadrangular, 

 a large epipodial veil on each side of the foot ; shell naticoid, 



cancellated, with velvety periostracum. Jurassic . Single 



genus: Narica. 



Fam. 5. Xenophoridae. — Foot divided by a groove, anterior 

 portion the larger ; central tooth heart-shaped, with blunt cusps, 

 lateral large, roughly triangular, marginals long, falciform; shell 

 trochiform, somewhat flattened, attaching various fragments 



externally. Devonian . Single genus, Xenophora (Figs. 



25, 26, p. 64). 



Fam. 6. Capulidae. — Ctenidium deeply and finely pectinate, 

 visceral sac scarcely spiral, penis long, behind the right tentacle; 

 shell roughly patelliform, with scarcely any spire, interior 

 polished, usually with a septum or internal plate of variable form, 



no operculum. Devonian . Principal genera (Fig. 155, 



p. 248) ; Capulus, shell cap-shaped, no internal plate ; Platyceras 

 (Palaeozoic, see p. 76), Diaphorostoma (Palaeozoic), Addisonia 

 (?); Crucihulum^ miQYWdl appendage funnel-shaped; Crepidula 

 (including Crepipatella and JErgaea)^ shell 

 slipper-shaped, with a large septum ; 

 Calyptraea (including G-alerus and Tro- 

 chita)^ internal lamina semi-spiral. 



Fam. 7. Hipponycidae. — Foot aborted, 

 animal sedentary, adductor-muscle shaped 

 like a horse's hoof, fastened on the ven- 

 tral side to the region of attachment, or 

 Fig. 272. -Two specimens of ^^ a thin calcareous plate which closes 

 Crepidula (marked a and the aperture like a valvc ; ventral side of 

 ^Mur^xrZixGmT^ ""^ ^^^ ^0^7 surrounded by a mantle with 

 papillose border, which corresponds mor-l 

 phologically to the epipodia, head emerging between the dorsal 1 

 and ventral mantles. Shell thick, bluntly conical, surface rugose. 



Eocene . Genera : Hipponyx ; Mitrularia^ a narrow half 



funnel-shaped appendage within the shell. 



Fam. 8. Solariidae. — Foot large, eyes sessile, near the outer 

 base of the tentacles, radula abnormal (p. 224) ; shell more or less 

 depressed, lip simple, umbilicus wide, margins often crenulated, 

 operculum variable. The proper position of the family is quite 

 uncertain. Ordovician . (i.) Solariinae. Genera: Sola- 



