518 F. M. MacFartanp, 
Mandibles strong and massive, the hinge region and grinding 
surface deep, reddish amber, the wing paler. Lateral wing thick, 
somewhat triangular, its dorsal border straight, the posterior and 
ventral borders rounded. The upper portion of the wing is thickened, 
its outer surface convex, the inner surface convex above, somewhat 
concave below. Upon the anterior inner surface is borne a shield- 
shaped plate, reflexed outward in front and forming the smooth, or 
sAehtly roughened masticatory surface. Above the mandibles are 
hinged together by a strong ligament in front, and immediately 
behind it by a chitinous band, triangular in cross section. 
Radula formula 2-.1.2%x32—35. Rhachidian tooth small, at the 
bottom of a deep median groove, widely separated from the laterals. 
Its base strong, squarish, notched in front, rounded behind, bearing 
a single, median spine directed obliquely upward and backward. 
First lateral larger, strongly depressed, its base elongate, linear, 
with rounded ends, bearing a single, strong spine, which is slightly 
curved, and bears on its inner face, near the base a series of from 
six to seven denticles, at times extending well up along the side 
of the spine. Outer lateral large, hamate, strongly compressed, its 
base long and curved, the tip of the hook blunt. The tooth is 
placed very obliquely on the upper margin of the radular groove, 
and is attached along the lower side of the base, instead of at its 
bottom. 
Glans penis short, conical; spermatotheca very small; oviduet 
long and wide. 
Habitat: Southern shore of Monterey Bay, California, and ad- 
jacent coast line, also taken as far south as San Pedro, California. 
In littoral zone, on rocky places, crawling on the brown algae, or, 
in quiet water, often floating, the sole of the foot uppermost, at the 
surface. Abundant during the summer months. 
Dirona albolineata MacFArLAnD Sp. Nor. 
(Plate 30 Eig:.2, Pl. 31-Fies. 11 19, Pl+32-Rie223% 
Body somewhat limaciform, everywhere smooth, tapering from 
the bluntly rounded head to the tip of the short, pointed tail. Head 
broad, squarish, bearing a broad, undulating veil, no labial tentacles. 
Foot elongate, broad and rounded in front, tapering posteriorly, its 
anterior margin smooth, undivided, sliehtly thickened. 
Rhinophores without sheaths, directed forward and outward, the 
