514, MAZATLAN UNIVALVES 
659. PIsaANIA INSIGNIS, Rve. 
Buccinum mutabile, (pars,) Val. Voy. Ven. Moll. pl. 6, 
f. 2, 2a-e, 1846; f.2¢, f.,2 a, B, excl. (non Linn.) 
B. insignis, Rve. Conch. Ic. pl. 8, f. 58, Dec. 1846. 
B. insigne, C. B. Ad. Pan. Shells, p. 69, no. 59. 
(Cantharus) Tritonidia insignis, H. & A. Ad. Gen. i. 85. 
Ifthe name of Val. was. published before that of Rve., the 
law of priority would require that this species should be called 
Pisania mutabilis; but as it was given in ignorance of its 
preoccupation in the or’ inal genus, and also to include both 
this species and P. gemmaca; and as Reeve’s name, given in the 
same year, is much more widely diffused, it is here retained. 
This beautiful, but by no means typical species varies in the 
height of spire, development of ribs, colour, and amount of 
basal twist. The nuclear whirls are smooth; those which 
follow are swollen, with the radiating coste always well deve- 
loped, and crossed by somewhat irregular spiral lirule, of 
which two are larger than the rest. On the ultimate whirls, 
the coste are often nearly obsolete, and are never produced to 
the base. Very fine lines are seen between the principal ones, 
which are at irregular distances. Colour purple brown, more 
or less spotted with white, especially at the tubercles of the 
two principal lirule ; mouth white, sometimes bordered with 
dark. When young, the shell somewhat resembles Fasciolaria, 
haying a few very slanting columellar folds, without labium or 
teeth. It is only when quite adult that the Pisanoid form is 
developed. Canal rather long, bent; labium rarely thickened 
so as to shew an umbilical chink. Labrum generally ribbed 
within. Operculum resembling that of Turbinella, but thinner, 
less twisted ; outside with irregular coarse strice of growth, 
and a channel along the outer edge; inside glossy, with a few 
irregular lines on the muscular scar. Colour olivaceous, with 
a yellowish tinge inside. The shell is rarely encrusted, even 
with Serpule and Bryozoa. The largest of the specimens 
measures long. 2°08. long. spir. 1°13, lat. 1°1, div. 40°. 
A transverse sp. ,, 1°44, - £68,051 OAS eae GOe: 
Hab.—St. Elena; in clefts of roeks at low water; Cuming.— 
Panama; not uncommon; in the same situation, but more 
frequently under stones, and especially under those which 
were lying on sand; C. B. Adams.—Mazatlan ; very com- 
mon; L’pool & Havre Coll. 
