Pl<icostyt*us.\ UASTROPODA. 763 



Fam. BULIMULIDJB, Fischer 



Animal having the jaw formed of folds imbricated externally and 

 meeting at an acute angle near the base. Radula with the central 

 tooth usually tricuspid ; lateral teeth bi- or tri-cuspid, the inner cusp 

 sometimes elongated and incurved ; marginal teeth with 2 or 3 small 

 cusps. 



Shell oblong or ovoid, sometimes conoidal or turreted ; aperture 

 longer than wide ; columella arcuate, not truncate anteriorly. 



Genus 1. PLACOSTYLUS, Beck. 1837. 



Placostylus, Beck, " Index Molluscorum," 57. Sole species : P. bootis, 

 Menke (a composite of P. fibratus and P. Hongii). Placostylus, Martens, 

 ; ' Die Heliceen," 1861, 185. Type : P. fibratus, Martyn. Placostylus, 

 Kobelt, Conchyl. Cab., ed. 2, 1891 ; Pilsbry, Man. Conch. (2), xiii, 19. 



Shell dextral, ovate or oblong, usually perforate, protoconch with 

 thimble-punctate whorls ; terrestrial species are solid or ponderous 

 and dark brown ; arboreal forms are thin and paler or variegated with 

 zigzag streaks ; the surface is often spirally malleated or corrugated ; 

 aperture ovate or ear-shaped, frequently of a characteristic orange- 

 red colour ; the outer lip is blunt and unexpanded or reflexed, with a 

 tendency to become abruptly narrower above ; columella generally 

 with a spiral fold, often calloused ; parietal wall calloused and bearing 

 a tooth, or simple. 



Distribution. New Guinea (one species), Solomon Islands, New 

 Hebrides, New Caledonia, Fiji Islands, Lord Howe Island, and New 

 Zealand. 



Two very able papers on the distribution of Placostylus, by Charles 

 Hedley, should be consulted (1) " The Range of Placostylus : a 

 Study in Ancient Geography " (P.L.S. N.S.W. (2), vii, 1892, 335) ; 

 (2) " A Zoogeographic Scheme for the Mid-Pacific " (I.e., 1899, 391). 



1. Placostylus Bollonsi, Suter, 1908. Plate 30, figs. 11, a, />. 



Placostylus Bollonsi, Suter, T.N.Z.I., xl, 1907 (1908), 340, pi. 25. 

 Shell large, oblong-conic, with a very obtuse apex, rimate, fairly 

 solid, axially closely striate, brown, peristome simple. Sculpture : 

 The first three whorls are finely and regularly axially costate and 

 mostly not punctate ; the third and sometimes the fourth and part 

 of the fifth whorl are distinctly broadly plicate at the suture above ; 

 the following whorls are densely wrinkle-striate, the striae of unequal 

 strength, slightly oblique and crossed by distant spiral strise, which are 

 mostly obsolete upon the base. Some examples show a secondary 

 axial sculpture on the fourth and fifth whorl, consisting of strongly 

 oblique costse, which are directed forwards, and reticulate the primary 

 axial sculpture, forming a more or less distinct network. On the last 

 two whorls a distinct narrow groove is margining the suture below. 

 Colour yellowish-brown, with numerous narrow blackish-brown streaks 



