OPISTHOBKANCHIATE MOLLUSCA FROM MONTEREY BAY. 133 



11. aigires albopunctatus MarFailaiid. 



.-Egires albcrpiiilclatiis MaoFarliiiiil, op. fit., p. 4.S. 



Body arched, not at all depressed, robust, highest and broadest immediately in front of the 

 branchial plumes and .sloping rapidly behind into the broad, bluntly rounded tail, in front more 

 gradually. Dorsum thickly set everywhere with short, blunt tubercules, cylindrical or with slightly 

 expanded apices, arranged in irregular rows. Frontal margin narrow, closely set with tuliercules, 

 continned behin<l the rhinophores as a tuberculate ridge, becoming less and less prominent until the 

 dcirso-lateral margin is at length marked only by an irregular row of tubercules, curving upward and 

 meeting the median dorsal row of the tail behind the branchiae. 



Foot narrow, linear, the sides nearly parallel, tapering abruptly behind into the bluntly rounded 

 tail, in front truncate, undivided, the angles simply rounded. 



Mouth small, inconspicuous, with a small, lobelike tentacle on each side. 



Sides of body set off sharply from mai^in of foot, smooth below and in front, behind and above 

 with thiee unequal rows of tubercules diverging slightly posteriorly. 



(iround color white or yellowish-white with irregularly scattered small, dark-brown spots, or 

 entirely white. Margin of liorsum and everywhere between the tubercules sprinkled with minute 

 dots of pure white. 



Rhinophores simple, cylindrical, truncate, 0.5 mm. long, completely retractile within prominent 

 tuberculate sheaths, the 5-6 tubercules and the margin being high on the outer side and quite low on 

 the inner one. Between the rhinophores a median longitudinal row of tubercules becoming irregular 

 behind. 



Branchial plumes 3, tripinnate, small, each one protected by a large irregularly tuberculate lolie 

 at its outer side. 



Length of large individual 13 mm., width 3.5 mm., height 4 mm. 



I'haryngeal bulb short, strong, nearly spherical in shape, about 2 mm. long, slightly less in height 

 and width, the radula sac projecting behind and below for 0.5 mm. The labial disc is convex, the 

 iipening triangular, clothed with rather thick cuticula. Above, forming the roof of the opening, is a 

 single, broad, thick mandibular plate, a narrow girdle of fine rodlike cuticular thickenings guarding 

 the opening. The mandibular plate (pi. xi.\, fig. 41) is quadrangular in form, its anterior cutting edge 

 very thick, straight, the posterior one much thinner, rounded and colorless. Width of mandible 345 jit. 



Radula broad, deeply grooved, colorless, except in the posterior rows, which are yellowish. Teeth 

 in 16-22 rows, the last two immature, the formula of the dentition 17-0-17. Rhachis narrow, naked. 

 I^leural teeth 17, similar in form, strongly hooked. Shaft with the usual thin, winglike process on 

 the inner margin, as shown in plate xix, figure 44, which repvc-rnt- tli.- tifth and sixth pleura of the 

 sixth row. The innermost tooth is the smallest of the pleum , tli.- -m r.<iling four increasing in size 

 pi. XIX, fig. 42), the remaining ones nearly ecjual, the outerii]ii--t one <lii_'litly smaller (pi. xix, fig. 43). 

 Length of innermost tootli 0.09 mm., the outermost about 0.09 mm., average length of- teeth from 

 middle portion of row 0.108 mm. 



The anterior genital ma-ss is plano-convex, the plane surface directed upward and inward, ellip- 

 tical, about 4 mm. long by 2 mm. broad. The spermatotheca is spherical, 1.2 mm. in diameter, and 

 lies upon the anterior upper border of the genital mass. Opening into it close together are the vaginal 

 duct and the oviduct, the former passing straight outward to the vagina, the latter short, receiving 

 the duct of the small pear-shaped spermatocyst and uniting with the h(riii.i|ilir.i.litic amiMilla. 



The penis (prasputium) is 0.450 mm. long by 0.210 mm. in diaimtcr and |.a!<scs i;iadually over 

 into the slender vas deferens. The retracted glans is cylindrical, short, lilnntly n.niideil at the end, 

 0.372 mm. long, its canal clothed with very minute, densely set hooks for 0.108 mm. of its length from 

 the tip. 



Habitat: Under overhanging rocks at low tide all along the coast from Monterey to Point 

 Lobos. \ot rare. Especially common upon sponges in a tunnel-like grotto formed by the waves near 

 Pebble Beach, on Carmelo Bay. Very sluggish in movement, shuns the light, and soon dies in 

 captivity. 



Type no. 181282, U. S. National Museum. 



