OPISTHOBRANCHIATE MOLLUSC A FROM MONTEREY BAY. 115 



Radula colorless, broad and short, about 4 mm. long by 3.5 mm. in width, deeply grooved, the 

 teeth in 33 rows, the last 3 immature. Rhachis very narrow, naked. Pleurfe multidentate with 42^9 

 strongly hooked, compressed teeth. The outer face of the pleural teeth convex, the inner concave, 

 the shaft bearing a large triangular, wing-like expansion on its inner margin, its upper edge thick- 

 ened, the inner thin. Numerous fine, ridge-like striations diverge from the inner margin of the shaft 

 and pass out into the wing throughout its whole extent, being especially prominent in the lower half 

 (pi. XVIII, fig. 3). Teeth increasing in size gradually from within outward (pi. xviii, fig. 2), the outer- 

 most ones decreasing rather rapidly, the general shape being retained (pi. xviii, fig. 1). Length of 

 shaft of innermost teeth 0.114 mm.; length of hook (perpendicular to longest axis of shaft) 0.054 mm. 

 Length of shaft of largest teeth of middle portion of row, about 0.240 mm.; length of hook of same, 

 0.150 mm. 



Salivary glands long, whitish, ribbon-like, about 2 mm. in diameter, in length 10-12 mm., extending 

 straight backward to the cardiac (posterior) end of thestomach. Stomachin antero-median cleft of the 

 liver, large, saccular, its cardiac end below and posterior, its pyloric end on left anterior side of the visceral 

 mass, the intestine curving upward and to the right along the upper anterior Ijorder of the stomach, 

 tlience backward in a deep groove in the dorsal surface of the liver to the anus. It is a slender, thin- 

 walled tube about 1 mm. in average diameter and 25 mm. long. 



Liver covered everywhere by the hermaphrodite gland, tapering posteriorly and rounded, in front 

 divided into two large lateral lobes by a broad median cleft occupied by the stomach. The left lobe 

 is rounded, the right with anterior and lateral flattened areas caused by pressure of the anterior genital 

 miiss. Bile cyst huL'c, .■l.im.'atcd, . yliiidrical, 4 mm. long by 2 mm. in diameter, opening into the 

 stomach cliisc to its canliar rnd and ciitiii'ly concealed by that organ, behind and below which it lies. 



Hermai)liri)(bti' ;:Uuiil, iloscly cuviTiriL' the whole surface of the liver, yellowish. The hermaphro- 

 ditic duct rises from the anterior end of the right lobe of the visceral mass with a diameter of 0.3 mm. 

 and is very short, dilating at 1 mm. length into the whitish ampulla. The ampulla passes forward in 

 a sinuous course, with an average diameter of 1 mm., to the anterior end of the genital ma-ss, where 

 it is closely looped into a coil and divides into the vas deferens and the oviduct. Its total length is 

 alxiut 24 mm., with an average diameter of 1 mm. 



The anterior genital mass is large, plano-convex in form, its flattened side dorso-posterior, nearly 

 circular in outline, its diameter about 11 mm., the convex surface directed outward and downward. 

 The ventral and posterior margins are sharp, the anterior and dorsal ones rounded and occupied by 

 the coils of the hermaphroditic ampulla and vas deferens, and the spermatotheca, respectively. 



The everted glans penis is conical, unarmed, long and rather .slender, about 7 mm. long by 1 mm. 

 in diameter at the base, the tip blunt and flattened, recurved upward and backward. The prseputium 

 is conical and thick, about 3 mm. long. The muscular vas deferens arising from it, describing a number 

 of closely coiled loops, pass<'s ainnt; the anterior external margin of the genital mass to its origin as a 

 branch of the hermaphroditic aiii|iiilla « ith no trace of a prostate gland along its course. Total length 

 of vas deferens when straiglitcn.d .mt alioiit L'S-30 mm., its average diameter 0.5 mm. 



The vaginal opening is situair.l ii nncdialcly liehind the penLs, above the duct of the nidamental 

 gland, its duct slender, 0.5 )iiiii n i.li . r.iiH-iii- nl.li(|uely upward to the posterior end of the spermato- 

 theca and opening into it after a sliirlitly sinuous course of about 1 mm. (pi. xviii, fig. 4, vd.). The 

 spermatotheca (pi. xviii, fig. 4, .yi.lh. ) is spherical, thin-walled, about 5 mm. in diameter, lying on the 

 upper margin of the genital mass and concealing the spermatocyst and its duct, which lie immediately 

 (jutside and belo\v it. It receives at its posterior end the very short common duct of the spermatocyst 

 and the vagina. The spermatocyst (pi. xviii, fig. 4, gp.c.) is elongate, pear-shaped, its length 3 mm., its 

 diameter 1.5 mm., pinkish in color, its duct as long as the cyst, with a diameter of 0.3 mm. and coursing 

 backward under the spermatotheca on the upper outer convex face of the genital mass to unite with 

 the very delicate uterine duct. The latter duct (pi. xviii, fig. 4, u.d.) 0.2 mm. long by 0.1 mm. in 

 diameter, runs forward and passes into the nidamental gland close to the oviduct. 



The nidamental and albumin glands form the greatest portion of the anterior genital mass and 

 consist of a peripheral more translucent portion made up of closely coiled tubules inclosing a denser, 

 more centrally placed white part, the other relations of the glands as usual in the genus. 



The species which is here identified with A. inontereijensig (Cooper) is comparatively common 

 in Monterey Bay, occurring in rocky tide pools at nearly all seasons of the year. It is especially 

 abundant on the piles of the wharf at Monterey, where it is found in company with the form next 



