MAZATLAJT TTNIVALTES 391 



The shells (of which I have examined about 100) scarcely vary, 

 except slightly in acumination. The operculum is formed like 

 an obtuse-angled triangle, with the base along the columella, 

 nucleus near the canal, the other angles rounded ; reddish 

 olive, strong, outside nearly smooth, with the base raised ; 

 muscular scar deeply marked, but not corrugated. The young- 

 est sp. is 1"1 long ; the largest (allowing for the decollation of 

 the spire) measures long. 2 "48, long. spiv. 1'34, lat. 1", div. 40". 



Sab.— San Bias, Kiener. — Gulf of California ; in sandy mud; 

 Lieut. Babb.—S. W. [Mexico ; P. P. C— Mazatlan ; rare, in 

 fine sand ; L'pool Co/.— (The localities "Gulf JS'icoya and 

 W. Coast Mexico, Hinds," assigned to P. ohvacea + funicidata 

 by Eeeve, probably belong to this species.) 



Tablet 1879 contains 3 sp. different ages, of which one has 

 the operculum in situ. — 1880, the largest sp. with its operculum, 

 mended after fracture ; the original part is from a terminal 

 nucleus, the new third from a central one. The shell has 

 twisted its canal till it is '56 broad, forming a broad false 

 umbilicus. Also a sp. incrusted, and with the canal destroyed 

 by sponge ; yet with the operculum in situ.— 1881, 2 opercula, 

 one normal, the other with a subcentral nucleus. 



458. Pleueotoma maculosa, Sow. 



Proc. Zool. Soc. 1833, p. 135.— Pi-e. Conch. Syst. vol. ii. pi. 233, 

 f. 8 -.— Conch. Ic. pi. 6, sp. '^o.—Mke. in Zeit. f. Mai. 1851, 

 p. 19, no. 89.— (Non P. maculata, C. B. Ad. Contr. Conch. 

 no. 4, p. 62. Jamaica.) 



DriUia maculosa, H. c)' A, Ad. Gen. i. 90. 



Shell very constant in form ; thin, slender ; of an ashy 

 colour, more or less spotted or stained with reddish brown ; 

 markings sometimes fine, sometimes in large dashes, sometimes 

 almost whoUy absent. Epidermis very thin, smooth, not 

 glossy. First three whirls smooth ; the rest with one row of 

 stoiit tubercles along the spire, wliich are rarely coloured ; the 

 whole surface very finely spirally striated. Canal open, too 

 long to rank satisfactorily with Drillia ; labrum smooth, sharp ; 

 posterior sinus large, deep ; anterior slight, open. Operculimi 

 closely resembling that of PL funiculata, but longer in propor- 

 tion, with the inner margin scarcely- raised. About one in five 

 of the opercida found were abnormal, with the nucleus central. 

 The smallest sp. of 11 whirls, measures '68 ; the largest, (with 

 15 whirls,) long. 1"96, long. spir. 1'13, lat. '57, div. 25". 



