PLATE XXXIX. 
I, 2. Trochus Duplicates. (Two-plaited Trochus.) Conical, shining; spire, with four volutions, with concave sides, 
with double, crenulated, spiral carina round base of each; base, with open umbilicus, margin of which with seven, promi¬ 
nent tubercles; aperture quadrangular. 
3, 4. T. Gibsii. (Gibs's Trochus.) Conical, short; spire, with four or five, flattened volutions, with obtusely carinated 
edges, on their upper parts concentric, spiral band, crossed by curved stria?; base convex, with concentric, radiating strife; 
umbilicus large, smooth; aperture rhomboidal; inner lip reflected over base of columella. 
5. T. Dimidiatus. (Divided Trochus.) Conical; surface rough, body flat on sides, concave above, with entire carina 
in centre; superior volutions convex, base convex, with carinated margin; aportnre pentangular; columella straight, solid. 
6, 7. T. Concavus. (Concave Trochus.) Conical; spire, with three, spirally striated volutions; with weak row of 
tubercles ; lower margin of each volution carinated ; base smooth, without umbilicus; aperture acutely rhomboidal. 
8, 9, 9*. T. Similis. (Similar Trochus.) Conical; spire, with four, flat-sided volutions, each with many, transverse 
ridges; several of ridges granulated. 
10. T. Dubius. (Doubtful Trochus.) Smooth, sub-conic; spire, with three, inflated, well-marked volutions; base 
rounded. 
II. T. Mantelli. (Mantell's Trochus.) Depressed, discoidal, with convex base; with plicated, wide, shallow, scalloped 
umbilicus; margin of which acutely angular; aperture oblong. 
12,13. T. Tiara. (Tiara Trochus.) Sub-conic, sub-depressed; body large; spire small, with divergent sulci and 
ridges; volutions, with two, obscure carince; body spirally striated; base produced, concentrically striated; with wide, 
deep umbilicus. 
14. T. Fasciatus. (Banded Trochus.) Conical; body large; spire, with six or seven, well-divided volutions, with 
spiral band round centre of each; base flattened; surface, with longitudinal, spiral stria?; aperture large, quadrangular ; 
columella, with single plait. 
15, 16. T. Monilifer. (Necklace Trochus.) Conical; volutions slightly produced, each with three, spiral rows of 
tubercles, and lower edges crenated; base convex, with six rows of regular granules, and centre smooth; aperture quad¬ 
rangular, oblique, margin entire, undulous, inside pearlaceous, columella truncated. 
17. T. GuttatUS. (Spotted Trochus.) Depressed, sub-conic; base wide; spire, with four volutions, at base of each a 
band of large granules; surface smooth, with rust-coloured spots. 
18. T. Linearis. (Lineated Trochus.) Conical, sub-depressed; volutions convex, transversely striated, with narrow, 
prominent, spiral fillet in centre and at base of each volution; base flat; umbilicus obscured by last volution; aperture 
transversely depressed. 
19. 20. T. Reticulatus. (Beticulated Trochus.) Conical, sub-turreted; body large; spire, with six, obliquely flattened 
volutions; upper and under margins, with broad, elevated carina; aperture obtusely quadrangular; base, with close 
umbilicus; with many, spiral, longitudinal striee. 
21. T. Anglicus. (English Trochus.) Conical; body large; spire small, with six or seven, sub-turreted volutions, 
with two spiral rows of depressed tubercles; three, strong, spiral stria3 invest surface, crossed by many, sharp, close striae; 
aperture quadrangular; columella imperforate; inner lip thickened. 
22, 23. T. Extensus. (Extended Trochus.) Depressed, conical; volutions elevated in centre, obliquely striated and 
with rugose undulations; base convex, smooth, with large, smooth umbilicus. 
24,25. T. Laavigatus. (Smooth Trochus.) Conical; body large; spire small, with six, inflated volutions; base 
convex; columella smooth, oblique, angular; aperture sub-rhomboidal, with smooth, glossy surface, and a few spiral 
grooves, crossed by fine strife; without umbilicus. 
26. T. Arenosus. (Sandy Trochus.) Conical, short, sub-turreted; volutions, with central, spiral band; base convex, 
almost smooth; with spiral, longitudinal sulci. 
27. T. Prominens. (Prominent, Trochus.) Conical, short, sub-turreted; spire, with four, convex, flattened volutions, 
with spiral sulcus around centre, and finely striated spirally, crossed by many undulations; sulcus crossod by minute strife. 
28. T. Bisertus. (Two-plaited Trochus.) Conical; sides flattish; base prominent; each volution with two plaits of 
small papilloe and with minute, longitudinal striee. 
29. T. Pyramidatus. (Pyramidal Trochus.) Conical; apex acute ; spire, with four, raised volutions and well-marked 
suture, and with oblique, longitudinal ribs; base flat; aperture sub-quadrangular. 
30. T. TornatiluS. (Turned Trochus.) Depressed; spire, with three volutions; body rounded on sides; a narrow, 
flattened space from insertion of outer lip, winding spirally along superior margin of volutions. 
31. T. PllllCtatUS. (Punctured Trochus.) Conical; sides flat; volutions, with many, minute, spiral stria?, crossed by 
longitudinal, undulating lines; between every two sets a narrow, spiral fillet. 
32. T. Sedgwickii. (Sedgwick's Trochus.) Conical, smooth; volutions, with obtuse, carinated edge and indistinct 
strife; base convex, with concentric striae; aperture rhomboidal, umbilicus closed. 
33. T. Elongatus. (Elongated Trochus.) Conical, elongated; with nine or ten, concave volutions, each with broad, 
prominent band at base, and obscure fillet somewhat below middle; with strong, spiral stria*, granulated near apex. 
34. T. Pallium. (Mantled Trochus.) Subconic, depressed ; body large; spire small, with three or four volutions, each, 
with band"of elongated, divergent tubercles ; body, with three series of tubercles; with divergent strife ; base convex, with 
tubercular, concentric stria?, umbilicated and plaited sometimes; margin, with large crenulations. 
35. T. Imbricatus. (Imbricated Trochus.) Pyramidal, sub-turreted ; volutions angular; each volution, with several, 
thread-like lines crossed by many, longitudinal stria?; base convex, striated like superior portion of shell; umbilicus closed. 
36. T. Abbreviates. (Shortened Trochus.) Conical, abbreviated; base of each volution, with produced, spiral fillet; 
with fine, spiral strife; base flattish, with sharp, concentric strife. 
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