H NILS ODHNER, NORTHERN AND ARCTIC INVERTEBRATES. V. FROSOBRANCHIA. 1 IHOTOCARDIA. 



Fissurisepta Seguenza 1863. 



Sliell oval, conic, depressed, but with an elevated apical part, tlie suninut of wliicli is taiicn up l)y tlie 

 subcircular foramen; sculpture consisting of radiating alternately larger and smaller, closely tuberculate striie ; 

 colour opaipic whitish. L. 2.9; Br. 2.3 inni F. granulosa Jeffreys 1882 



(= F. papulosa Jeffkeys 1870, not Seguenza 1863.) 



Emargiiiula Lamarck 1801. 



I. Sculpture reticulated of coarse and sparse longitudinal cords, mostly intermixed 

 with smaller ones, and concentric ribs of about the same strength; colour white. 

 L. 9—16 mm E. fissura (Linne 1758) 



(= E. reticulata Sowerby 1813). 



PI. 2 figs. 42 — 45. 



II. Sculpture consisting of broad longitudinal fascicles of riblets alternating with 

 finer threads and crossed by fine and close concentric lirse; colour white. 

 L. 25—37 mm . E. crassa Sowerby 1813. 



ri. 2 figs. 46—50, PI. 3. figs. 1 — 2. 



Proi»ili<lium Forbes & Hanley 1849. 



Shell oblong, depressed, with subeentral apex, sculptured by fine and close-set 

 radiating striae, granulated by crossing concentric ones; apex distinctly twisted; colour 

 whitish. L. 4.3 mm P. ancyloide (Forbes 1840). 



PI. 2 fig. 24. 



Fam. Trochidae. 



Animal with frontal lobes; jaws present; radula often with more than 5 lateral 

 teeth on each side (subfam, Gibbulinse). 



I. Aperture quadrangular (not rounded); columella dentated or sinuated at base; 

 outer lip smooth; shell solid, usually variegated and strongly sculptured. 



A. Shell umbilicated, usually spirally ribbed, but without sharp keels at the 

 suture; radula oo . 1 . (5 . 1 . 5) . 1 . oo, the rhachian tooth with its basal plate 

 broader than long Gibbula Risso 1826. 



B. Shell imperforated, smooth or spirally keeled or granular; often a sharp 

 ridge at the suture; radula oo . 1 . (4 — 5. 1 . 4 — 5) . 1 . oo, the rhachian tooth 

 usually with a longer than broad basal plate Calliostoma Swainson 1840 



( = Zizyphinus Gray 1840). 



II. Aperture rounded; columella with a strung tootii below; outer lip thickened and nodulous within; shell 

 solid, uniforndy brownish; whorls rounded, sculptured witli spiral cords and longitudinal lamellae 



Craspedotus Philippi 1847 f = Danilia Beusina 1865). 



III. Aperture rounded; columella simple; shell usually thin, smooth or variously 

 sculptured but always unicoloured. 



A. Radula with numerous (> 40) lamellse with recurved apex, denticulated on 

 both sides; the lateral tooth incomplete (without cusp); shell smooth or 

 spirally sculptured Margarita Leach 1819, 



