ANCULA. 233 



Family TRIOPID^E. 



Teeth, many in each cross series (rarely only four), the inner 

 lateral ones large, irregular shaped. Mantle small, edged with 

 tentacular appendages ; gills on the middle of the hinder part of 

 the back, in a common cavity, surrounding the vent ; vent dorsal. 



In this family the body is somewhat angular, and the mantle is 

 distinct and furnished with tubercular appendages ; the species of 

 the genera comprising this group constitute some of the most deli- 

 cate and beautiful forms of Nadibrancldate Mollusks. 



Oeiiiis Al^CULA, LovEN. 1846. 



Body elongated, slender ; mantle adherent throughout and fur- 

 nished with styliform dorsal cirri ; labial veil produced on each 

 side into a short papilla ; tentacles perfoliate, armed with styles at 

 the base. 



Ancula sulphurea. 



Plate XXII. Figs. 310, 314. 



Body long, slender, light brownish ; branchial plumes three, arranged in semi- 

 circle, anterior largest, doubly pinnate ; surrounding tentacular processes eight to 

 twelve, sulphur tipped ; oral tentacles long, the processes arising from their very 

 base. 



Ancula sulphurea, SriMPSON, Mar. Invert. Gr. Manan, 26 (1853) ; Check Lists, 4 (I860). 



Body slender, very light brownish, transparent ; dorsal tentacles 

 large, club-shaped, the upper third with al)out twelve laminae of a 

 sulphur-yellow color, the appendages arising from the very base, 

 almost as if from the body, and tipped with yellowish brown ; oral 

 expansions rather long and tipped yellow ; branchial plumes three, 

 arranged in a semicircle, the anterior the largest, doubly pinnate, 

 with a series of dots on tlie main branches, delicately transparent 

 and sulphur tipped ; the main branches surrounding tentaculiform 

 appendages eight to twelve, sulphur tipped. Foot narrow, rounded 

 at the sides, sometimes contracting to a mere line. Length, often 

 an inch and a quarter. 



Very common under stones in the Laminarian Zone ; Grand 

 Manan, among corallines, on Zostera, and under stones in Boston 

 Harbor, June, 1850, and May, 1851 (^Stimpson). 



