MARINE MOLLUSCA OF THE UNITED STATES. 81 
Genus ARCHITECTONICA, Bolten. 
Mus. Bolt. 1798. 
Solarium, Lamarck, Prodr., 74. 1801. 
The species of this genus are fancifully called ‘‘stair-case shells” 
from the appearance of the spiral edges of the whorls in the per- 
spective umbilicus. Distribution tropical. 
1. A. GRANULATA, Lamarck. Fig. 150. 
(Solartum.) Anim. s. Vert., vii. 3. 1822. 
Shell conoid, yellowish flesh-color, stained with livid-purple, . 
sparingly belted with distant chestnut-red spots and dots; whorls 
spirally grooved and granosely warted ; base many crenated ; um- 
bilicus rather small. 
North Carolina to West Indies. 
Genus LACUNA, Turton. 
Zool. Journ., iii. 190. 1827. 
The Lacunez feed upon sea-weed, and Lovén observes that when 
the fuci are of a brown color these animals become green, but if 
red they assume a rosy tint. They principally inhabit the shores 
of northern countries, and several species are common to both 
continents. 
1. L. pivaricaTa, Fabricius. Fig. 151. 
(Turbo.) Fauna Greenl,, 392. 1780. 
T. vineta Montagu, Test. Brit., 307, t. 20, f. 3. 1803. 
T. quadrifasciatus, Fleming, Brit. Anim., 299. 1828. 
L. pertusa, Conrad, Journ. Philad. Acad., vi. 266, t. 11, f. 19. 1880. 
Shell small, thin, ovate-conic; spire pointed; whorls five, very 
convex, with faint incremental lines; suture deep ; aperture nearly 
circular; lip sharp and simple; pillar-lip with a wide and deep 
groove behind,.ending in a profound umbilicus; color yellowish, 
with sometimes four or five dark purplish or reddish bands. 
Length 7.5 mill. 
New England to New York. (Hngland.) 
2. L. NERITOIDEA, Gould. Fig. 152. 
Amer. Journ. Science, xxxviii. 197. 1840. 
?L. pallidula, Turton (var.), Zool. Journ., iii. 190. 1827. 
Shell small, thin, hemispherical, or obliquely ovate; whorls 
three and a half, regularly convex, minutely wrinkled near the 
suture, and with an occasional transverse scratch, otherwise 
6 
