CLA8R TV 



GASTROPODA 



539 



Superfamily 3. TAENIOGLOSSA Bouvier. 



Teeth of the radula seven in each transverse roiv. Mainly holostomate forms, hat 

 some (jenem have deeply notched apertures, as in the higher divisions. 



Family 1. Purpurinidae Zittel. 



Thick-shelled, oval, with platform-like spire, and with- 

 out pearly layer. TVJiorls flattened heneath the suture and 

 angular, the angles often heset with nodes. Body whorl 

 large ; aperture oval, with anterior emargination, and 

 discontinuous peristome. Operculum unknown. Carboni- 

 feroiis to Cretaceous. 



Trachydomia Meek and Worth. {Trachynerita Kittl). 

 Goal Measures ; North America and Europe. Pseudoscalites 

 Kittl ; Tretospira Koken. Trias ; Europe. 



Purpurina d'Orb. Elongate-oval. Whorls angiilar 

 superiorly, sj)irally ribbed, with transverse folds or costae, 

 highly ornamented, often with umbilical fissure. Aperture 

 oval, anteriorly notched. Rhaetic and Jura. Furpuroidm noduiata (Young 



n -TT j.i. /ny- r\ n A \ c< • • J.^ • and Bird). Great Oolite ; Minchin- 



Furpuroidea Lycett (Fig. 924). Spire with successive hampton, England. 

 Steps or platforms, the flattened surface beneath the suture 



bounded by a row of nodes. Last whorl inflated, smooth. Aperture anteriorly with 

 canal-like notch ; outer lip thin. Jura and Gretaceous. 



Brachytrema Morris and Lycett ; Tomocheilus Gemm. Jura. 



Fig. 924. 



Family 2. Littorinidae Gray. 



Shell turhinate, usually smooth or spirally ornamented, without nacreous layer. 

 Aperture rounded ; outer lip sharp. Operculum horny, paucispiral. Marine. 

 Ordovician to Recent. 



Fossil Shells of this family are distinguished solely from those of the Turbinidae 



and Trochidae by the absence of a pearly layer. The animal, 



however, differs radically. The heart has but one auricle in 



the Littorinidae, two in the Turbinidae and Trochidae. The 



radula in the last-named groups is rhipidoglossate ; in the 



present family it is taenioglossate. The differences.in essen tial 



structure are thus seen to be considerable ; yet the sliells 



when fossilised are so similar, it can scarcely be doubted tliat 



the so-called Paleozoic Littorinidae are in many cases very 



closely related to genera referred to the Turbinidae and 



Trochidae. The limits of these families are therefore very 



Ym, 925. uncertain, so far as Paleozoic forras are concemed. Among 



Turhoniteiia subcostafa the extinct genera which exhibit great similarity to Littorina, 



(^"i^^f;)- Middie üevonian ; j^^^; are often assigned to the above-named families, may be 



Paffrath, near Cologne. , , „°, . „ , xx n r\ j • • ^ 



mentioned the followmg : Holopea Hall. Ordovician to 

 Devonian. Turhoniteiia de Koninck (Fig. 925). Devonian and Carbonil'.ioii>. 

 Portlockia, Turhinilopsis and Rhahdopleura de Koninck. Lower Carboniferous. 

 Lacunina Kittl. Tiias. 



Littorina Fer. (Fig. 926). Thick-shelled, turbinate to globose, smooth or s])ii-al]y 

 striated, without umbilicus. Aperture oval. Jura to Recent. 



