MAZATLAN UNIVALVES 455 
Triton nodosum, Whe. in Zeit. f. Mal. 1850, p. 189, no. 78. 
Murex argus var. 0. pars, Gmel. 3547, no. 78. 
Triton Chemnitzii, Gray in Zool. Beech. Voy. p. 110 61839.)— 
Rve. Conch. Ic. pl. 11, f. 37.—C. B. Ad, Pan. Shells, p. 115, 
no. 126. 
Fusus Wiegmanni, Anton, Verz. p. 77, (1839.)—Phil. Abbild. 
pl. 2, f. 2, 4 var. 
Lagena Wiegmanni, H. § A. Ad. Gen. i. 104. 
Cassidaria setosa, Hinds, Pubi. 
Triton perforatus, Cour. Proc. Ac. N. 8. Phil. vol. iv. p. 156 
(Feb. 1849) :—Journ. A. N. S. Ph., n. ser., vol. i. p. 280, 
pl. 39, f. 6 var. 
Shell ventricose ; very thin or rather solid; spire more or 
less elevated ; shoulder either round, or (usually) with a more 
or less developed rounded keel; canal varying in length and 
twist, shewing more or less of an umbilical chink ; colour 
tawny, sometimes with the spiral ribs purplish brown. Mouth 
and spire often seen without varix; penultimate varix either 
absent, or at variable distances from the last, which is not 
prominent, sharply serrated by the projections of the internal 
teeth which are generally grouped in pairs. Labium nearly 
smooth, or with more or less prominent white corrugated teeth 
on a purplish brown ground. Nuclear whirls smooth, turrited, 
deciduous, fixed slanting on the rest, which are at first cancel- 
lated, afterwards only with spiral cost, sometimes obsolete. 
The epidermis is extremely thin and deciduous, crossed by 
more or less frequent scaly rows, ending in bristly hairs. 
The opercula were unfortunately not sent. The shells are 
free from incrustations. The largest of the specimens mea- 
sures long. 4 66, long. spir. 1°66, lat. 3°04, div. 70°. 
A small rounded sp. ,, 3°12, a 12.55, Gh ZL ee 
A broad sp. a oO) a 125 ee 00s Oe 
Tablet 2064 contains 1 sp. rounded whirls.—2065, 3 sp. nor- 
mal state.—2066, 3 do, colour developed.—2067, 2 do. keel 
developed. — 2068, 5 sp. shewing variation in varices ; the 
ultimate and penultimate being distant 100°, 140°, 210°, 250°, 
and 300° respectively.—2069, 2 sp. one with penultimate varix 
swollen but not marked off; the other do. foliated. — 2070, 
2 sp. one with spiral coste broad and distant; the other do. 
nearly obsolete.—2071, 1 sp. mended after fracture.—2072, 1 sp. 
after hot acid process, varix forming. 
