MONODONTA. 115 



narrow spiral bands, finely articulated with red or purple and white ; 

 spire conical, elevated ; sutures distinctly impressed ; apex minute 

 and acute when not eroded ; whorls 6, convex, quite smooth outside, 

 but when eroded the nacre is seen to be finely spirally lirate ; base 

 not eroded ; aperture very oblique ; outer lip narrowly margined, 

 acute, iridescent within, the nacre smooth, but apparently lirate; 

 columella arcuate, concave, white, thin, covering the place of the 

 umbilicus with a pad of callous, the outer edge of which is usually 

 not appressed closely to the base; parietal wall with a thin translu- 

 cent callous or none; umbilico-columellar callous bounded outside by 

 a more or less obvious streak of blue, green, brown, or sometimes 

 light yellowish. Alt. 21, diam. 24; alt, 21, diam. 21 mill. 



Cape Region of S. Africa. 



Trochus sagittiferus LAM., An. s. Vert., vii, p. 29. PHILIPPI, 

 Conchyl. Cab., p. 150, t, 24, f. 16. FISCHER, Coq. Viv., p. 180, t. 59, 

 f. 3, t. 103, f. 4 (excl. synonymy !). T. variegatus ANTON, Verzeich., 

 p. 57. PHILIPPI, Conchyl. Cab., p. 144, t. 24, f. 6, 15. T. impervius 

 PHILIPPI, Conchyl. Cab., p. 145, t. 24, f. 8. T. perdix KOCH, in 

 PHILIPPI, Conchyl. Cab., p. 150, t. 24, f. 17. 



Plate 24, fig. 94 is T. variegatus Anton ; fig. 91 is T. perdix Koch ; 

 pi. 35, figs. 28-32 represent T. impervius Phil. 



This form may be distinguished from the preceding by its smooth, 

 not striate nor lirate surface ; its columella is arcuate, con- 

 cave or sometimes substraightened in the middle, but is never dis- 

 tinctly convex and lobed there as in M. sauciata ; the outline of the 

 shell is more compact and elevated, the aperture smaller, and the 

 coloration, while sometimes approaching that of M. sauciata, is 

 generally quite distinct, 



M. FULGURATA Philippi. PI. 35, fig. 16 ; pi. 23, figs. 68-70. 



Shell imperforate, conoidal, rather thin, apex subacute ; whorls 5, 

 moderately convex, nearly smooth, the upper ones eroded, spirally 

 striate, yellow ; the remainder margined and compressed at the 

 sutures, greenish, ornamented with narrow brownish, obliquely 

 radiating, zigzag lines; last whorl rounded, slightly descending; 

 aperture subovate, sulcate within ; columella arcuate, compressed ; 

 umbilical tract white, callous. Alt. 19, diam. 18 mill. (Fischer.) 



Coast of Guinea. 



T.fulguratus PHIL., Zeitschr./. Mai, 1848, p. 106 and Conchyl. 

 Cab., p. 268, t. 39, f. 10, 11. FISCHER, Coq. Viv., p. 181, t. 60, f. 1. 



