302 MAZATLAN UNIVALVES 
yum levibus, parum elevatis, haud (normaliter) separatis : intus 
convextore, cicatr. muse. mediano, circulari, magna, trreguiariter 
concentricée rugulosd ; marginem versus anfractus monstrante. 
Vermetus centiquadrus, Val. Voy. Ven. pi. 11, f. 1, 1a, la dis. 
+ Vermetus Peronii, Vail. loc. cit. f. 3, 3a. 
The operculum appears intermediate in character between 
the regularly multispiral operculum supposed to belong to a 
species of this group, and the deeply concave, paucispiral 
operculum of Siphonium giganteum. One specimen found in 
situ, (by which, along with two others scarcely admitting of 
doubt, the rest were identified,) has not more than half the 
diameter of the aperture. Most of the few found were more 
or less irregular; the edges having a tendency to separate 
elevation, and the whirls to become fewer after fracture. 
The V. Peronii, a group of which is figured on Strombus 
galea, fixing the locality of the species, appears only to differ 
from V. centiquadrus in the absence of punctures: but as both 
states are frequently found on the same specimen, it cannot 
warrant specific separation. 
The shell is loosely adhering, and of very irregular habit of 
growth: when spiral, with rapidly diverging whirls. The 
sculpture is close, and seldom much impressed. The colour is 
laid on here and there in blushes. An average specimen 
measures as it stands long: 2°4, lat.1°4, diam. °4A4. 
fTab—Mazatlan ; not uncommon on Spondylus and Chama ; 
also on stones and other shells ; L’pool & Havre Coll. 
Tablet 1476 contains an extremely young sp. with apex en- 
veloped ; also one somewhat older.—1477, a young sp. growing 
straight, on Conus gladiator.—1478, an adolescent sp. covering 
an extremely deformed Crepidula aculeata. On the back are 
some egg-cases, and on the same tablet a similar group.—1479, 
2 sp. intertwined with spiral growth; also a fragment shewing 
septa.—1l480, asp. on Vitularia salebrosa. On reaching the 
canal, it has left its mouth, and twisted back at right angles.— 
1481, aspecimen on rock, growing upwards, spirally twisted on 
itself.—1482, a large group off Spondylus, with Petaloconchus, 
Annelids, &c.—1483, an operculum as found in a fragment of 
the shell ; also 4 separate opercula, of which 3 are abnormal. 
352 6. ALETES ? CENTIQUADRUS, var. IMBRICATUS. 
_ A.t. “A. centiquadro” simili, sed colore intensiore ; rugulis 
spivalibus parvis, confertissimis, haud decussatis, squamulis 
