130 MANUAL OF THE :\JOLLUSCA. 



brancliial pliune single, long ; lingual ribbon linear ; teeth single, hooked, 

 denticulated ; uucini 3, the iii-st transverse, 2 and 8 claw-shaped. 



Fig. 80* 



Bistr., 3 sp. Labrador, Norway, Brit., Medit. W. Africa. Range, — 

 100 fnis. 



Fossil ; see Pteroceyas and Bosiellaria ; above 200 species, ranging from 

 the lias to the chalk, probably belong to this genus, or to genera not yet 

 constituted. I 



Struthiolaria, Lam. ' 



Etym., struthio, an ostrich (-foot), from the form of its apertm'e. 



Type, S. straminea, PI. IV., fig. 6. 



Shell turreted ; whirls angular ; apertm-e truncated in front ; columella 

 very oblique ; outer lip prominent in the middle, reflected and thickened in 

 the adult ; inner lip callous, expanded ; operculum claw-shaped, curved in- 

 wards, with a projection from the outer, concave edge. 



Animal with an elongated muzzle ? tentacles cylindrical ; eye-pedicels 

 short, adnate with the tentacles, externally ; foot broad and short (Kiener.) 



Distr.y 5 sp. Austraha and Xew Zealand ; where alone it occurs sub- 

 fossil. .. 

 FAMILY IV. Melaniad^. \ 



Shell spiral, turreted ; with a thick, dark epidermis ; apertm'e often 

 channelled, or notched in fr'ont ; outer lip acute ; opercuimn homy, spiral. 

 The spire is often extensively eroded by the acidity of the water in which the 

 animals live. 



Animal with a broad non-retractile muzzle ; tentacles distant, subulate ; 

 eyes on short stalks, united to the outer sides of the tentacles ; foot broad and 

 short, angulated in front ; mantle-margin fringed ; tongue long and linear, 

 with a median and 3 lateral series of hooked multi-cuspid teeth. Often 

 viviparous. Inhabiting fresh- water lakes and rivers throughout the warmer 

 parts of the world. Only fossil in Britain. 



* Fisr. SO. Aporrhais pes-pelecani, L., from a drawing by Joshua Alder, Esq., n 

 the " British Mollusca." 



