download pdf

RISSOIDAE 137
C. Interspaces with silky, wavy crinkles; 3 mm.; Coronado Islands
cleo Bartsch
Interspaces smooth, 3 mm.; CataHna Islands, south californica Bartsch
D. Whorls decidedly inflated; 3 mm.; Monterey south bakeri Bartsch
Whorls not inflated E
E. W^ith very fine, numerous axial threads (48 to ^^ on last whorl) .
F
With coarse riblets (36 on last whorl; 14 on next to last); 3 mm. Alaska
to Monterey neivcovtbei Dall
F. Shell slender; 2 mm.; San Pedro south dalli Bartsch
Shell not as slender; 3.5 mm.; Redondo Beach south
coronadoensis Bartsch
Key to the Atlantic Coast Rissoina
A. Shell sculptured with riblets or spiral lines B
Shell smooth, glossy-white; 4 mm.; Carolinas, Florida, and West Indies;
syn.: laevigata C. B. Ads. brouoniana Orbigny
B. With axial ribs more prominent than spiral threads C
With axial ribs not more prominent than spiral threads . . . . F
C. Axial ribs only D
Axial ribs and spiral threads both present E
D. 4.5 to 6.0 mm.; white or stained yellow; 16 to 22 ribs; South Florida and
the Wgsi Indies bryerea Montagu
3.0 to 5.0 mm.; white; 1 1 to 14 ribs; suture sometimes deep; North Caro-
lina to Florida and the West Indies chesneli Michaud (PI. 2 2u)
E. 4 to 5 mm.; ribs strong but disappearing on base; spiral threads strongest
on base; white to rusty; southeast Florida and the \\ est Indies
vndticostata C. B. Adams
6 to 7 mm.; 25 to 28 low, weak ribs, spirally striated or pitted between;
glossy; white to yellowish; North Carolina to the West Indies
deciissata Montagu
F. Sculpture strongly cancellate G
Not strongly cancellate; low, spiral threads dominant; axial ribs faint;
weakly cancellate; 5 to 10 mm.; southeast Florida and the West
Indies striosa C. B. Adams
G, 5 to 7 mm.; white; strongly cancellate; depressed interspaces large and
square; southeast Florida and the West Indies cancellata Philippi