Page 6 October 1977 No. 235 NEW YORK SHELL CLUB NOTES 
scribed in the Veliger, Vol. 11-3, .P.257,5 Berkeley, 
Calif. U.S.A. 
stohleri Cate & Schilder, 1968: from Siasi, Sulu Sea, Philippines, 
. Also unique and likely to remain so as ie 
eres abet te be just S tarse. odd form of contaminata Sow. 
which also has its center of distribution in the Sulu 
Sea. Described in the Veliger, Vol. 10-4, P.382, Berke- 
ley, Calif. U.S.A. 

ARTICLE OF THE MONTH 
"A description and experimental analysis of Batesian mimicry between 
a marine gastropod and an amphipod" is the title of a paper by Lau- 
rence H. Field in Pacific Science 28 (4):439-447, October 1974. His 
studies indicate that the gastropod Lacuna is mimiced by the amphi- 
pod Stenopleustes, both of which inhabit the blades of eel grass. 
If Stenopleustes swims, betraying its snail disguise, it is readily 
eaten by fish. These data suggest that the amphipod is enjoying a 
protective advantage from its mimicry of the relatively inedible 
Snail Lacuna. 
G At w& Henry D. Russell 
WHAT SHELL IS THIS? 
Morris K. Jacobson 
In 1843 James DeKay (NATURAL HISTORY OF NEW YORK, MOLLUSCA & CRUSTA- 
CEA, p. 107, pl. 6, fig. 104) described a strange shell in the fol- 
lowing terms: "Shell moderately solid, subconical; its transverse 
exceeding its vertical diameter. Whorls four or five, convex; the 
body-whorl very large, subinflated. Seven to nine distant revolving 
costae on its upper surface, which is separated from the simple 
Striate surface by an obsolete carina (= faint keel. mkj). Spire 
scarcely much elevated, faintly striated; umbilicus large and very 
profound; aperture oblique; lip thin and simple, entire (= not in- 
terrupted. mkj). Color: bright red." He called it Margarita or- 
nata, and remarked: "I have met with many specimens of this beauti- 
ful shell, collected on the shores in the neighborhood of New York." 
The illustration of the shell is about 4 inch in diameter and 4 inch 
high, decorated spirally by six reddish-brown lines separated by 
wos ragapages erp ppd oe: wide as the lines. The only other com- 
met on 1s species is by A. E. Verrill (INVERTEBRATE ANIMALS 
OF VINEYARD SOUND, 1873, Pp. 661). He writes: ee described 
as occurring in the vicinity of New York, but I have not met with it 
in Long Island Sound." My query is: Has anybody? 
At first sight it seems to be a sort of Littorina ob ast 
as far as the thin lip, the uninterrupted body host atthe eacll 
spire'are concerned, But obtusata does not have a "large and pro- 
found" umbilicus; as a matter of fact, like all Littorina. it has 
no umbilicus at all. Nor can obtusata ever appear in "bright red" 
color, for all its numerous variations. Yet assuming that Mr. DeKay 
was a sober (in more senses than one) observer, he must have collec- 
ted something in so many specimens. What was it? 
If Margarita ornata ever did occur in i 
f ; our area, it could not have 
disappeared; as a matter of fact, the very opposite siddid nave 
—————————————eeSseswoa ee __O ee ———SaaE 
