PLANISPIRA. 115 



Keisen im Archip. Phil., Landmoll., p. 163, anatomy of H. vittata. 

 Not Eurystoma Raf. 1818, nor Eurystomus Vieill., 1816. Philidora 

 de MORGAN, Bull. Soc. Zool. France, 1885, p. 384 (proposed for P. 

 wrayi and hardouini). 



Shell varying from discoidal to depressed-globose, umbilicate, the 

 surface rather roughly sculptured, hairy when young, microscopically 

 granulated, sometimes ribbed when adult ; the apex typically show- 

 ing no distinct sculpture. Last ivhorl strongly deflexed in front. 

 Aperture very oblique, small, the lip well expanded, reflexed below, 

 the terminations approaching and sometimes connected by a raised 

 callus. Type P. asperella, pi. 19, fig. 25. (See also pi. 19, fig. 24, 

 P. vittata; and pi. 19, fig. 23, P. vittata var. spi?iolce). 



Animal (of P. delibrata) having the left body-lappet of the mantle 

 represented by a simple thickening ; right lappet reaching anteriorly 

 over the back and rapidly becoming narrower below. In P. vittata 

 the sole is indistinctly tripartite. 



Jaw arcuate, the entire anterior surface ribbed, the seven median 

 ribs stronger (pi. 32, fig. 44, P. delibrata. PI. 34, fig, 5, P. trochalia). 

 In P. vittata there are five very high ribs, strongly denticulating 

 the margin. 



Radula (of P. delibrata) very long, with 124 transverse rows of 22 

 (to 18) 20.1.20.18 (to 22) teeth. Central and inner lateral teeth with 

 a large mesocone and obsolete side cutting-points; outer laterals and 

 marginal teeth with the ectocone developed. In P. vittata the 

 formula is about the same ; central and inner 14 laterals unicuspid ; 

 outer laterals with an ectocone. At the 25th tooth the mesocone 

 becomes bifid, and outwardly the bifid mesocone becomes shorter, 

 the outermost marginals having three subequal cusps. See also pi. 

 34, fig 4, P. asperella, and pi. 34, fig. 6, P. trochalia. 



Genitalia having the female side free from all accessory organs, 

 the duct of the spermatheca very long. Penis terminating in an 

 epiphallus near the root of which the retractor is inserted ; epiph- 

 allus long, terminating in a short flagellum and the vas deferens (pi. 

 32, fig. 45 P. delibrata'). The genitalia of P. vittata are similar ; 

 penis with a spirally coiled flagellum. In P. penangensis (pi. 42, 

 fig. 6) the penis bears an epiphallus ending in a short flagellum, and 

 has an accessory sack, perhaps an " appendix." 



Distribution, India, Burmah, Ceylon, Mergui Archipelago and 

 Sumatra. 



