146 HULLETIN OF THK BUREAU OF J-ISHERIES. 



hudsoni and the following form here ilcprrilxvl, niiiih are tlie only ones of this jrenus ; 

 Monterey Bay or its vicinity. 



The specific name here given is in recognition of tlic masterly work i.f my friend 

 Hudson in the illustration of various animal forms. 



Type no. 181289, U. S. National Museum. 



18. Acanthodoris brunnea MacFarland. 



Araitlhodoris briinnca JlacFarland, op. fit. p. 52. 



Body outline oval, convex, broadest in front almiit in the rej.'ion of the rhinophores, the mantle 

 firm and thickly set everywhere with conical tulien nh- ha\iii'j muhdcl tips (PI. xxix, figs. 21, 21).) 

 Tubercules of varying size and of no definite arrun^Mincni -;i\r ihat the smaller ones almost invariably 

 alternate with the larger (about 1 mm. in diameter i. Mantl.- e\ciy«liere covering the foot excejit 

 posteriorly when the animal is in motion, its margin broad and rather thick. General color of dorsmii 

 brown, flecked with irregular blotches of black in varying amount (pi. x.xix, fig. 21). Between the 

 tubercules numerous small spots of light lemon yellow, the mantle edged more or less completely with 

 the same color. Stalks of branchial plumes yellowish brown, marked on the inner side with twn 

 narrow longitudinal lines of dark brown, the branchia; tipped with lemon yellow. Rhinophores <leep 

 blue-black, tipped with yellowish white. In alcoholic specimens the general darker color is well 

 retaine<l, the yellow tending to disappear. 



Total length of animal 19-22 mm., width it-l.i mm., lunght 7-9 nun. 



Head large, veliform, concealed by mantle (pi. xxix, tig. 21 ), continued laterally into the wide Hat 

 tentacles, in front with a slight median concavity. Tentacles broad, recurved, bluntly pointed at tij^s, 

 their anterior curved margin thin. Mouth a longitudinal slit. Foot oval, nearly quadrangular, it- 

 anterior and posterior ends bluntly rounded. (General color of under surface yellow, the lower faic 

 of mantle, the head, tentacles and sides of body sprinkled with fine dark brown or black <lots. 



Rhinophores long, cylindro-conical, tapering to blunt tips, inclined forward and outward, perfoli- 

 ate with 20-28 thin, slightly oblique lannniv, the lower ones occupying the front of the clavus only 

 (pi. XXI, fig. 104). Stalk one-half the length of the laminate portion. Color deep lilin'-lilack, ti|i|ied 

 with yellowish white, the lamiufe edged with a very narrow line of white. ii"t imtKcalile w illumt a 

 hand lens. Fully extended length, 8..5 mm. Retractile within a low sheath, tin- margin nt whicli is 

 prolonged into 6-8 lobes resembling the dorsal tubercules, but somewhat fiattened. Three of these 

 are as high as the dorsal tubercules and are placed at equidistant intervals, one external, the other two 

 antero-median and postero-median, respectively, the intervals between them V)eing occupied by lower 

 similar ones (pi. xxi, fig. 104). 



Branchial plumes 7, wide spreading, bipinnate, nonretractile within a sheath, arranged in an 

 incomplete circle about the anal papilla on posterior dorsum. About 10 tubercules are included 

 within the rosette, 4-5 of them large and inclosing the anal papilla, which is about one-lialf the height 

 of the largest tubercules, and is edged with a narrow line of j'ellow. 



Pseudo-peritoneum thickly sprinkled with fine black pigment. Blood gland lobulated, whit.-, 



placed transversely upon the central nervous system, overlapping in front the large proximal i - 



voluted portion of the salivary glands, which is coiled at the sides and upon the small o>sophageal 

 diverticulum. 



The pharyngeal bulb is strong, its height, including the crop, is 3 mm., length 2.3 mm., width 

 2 mm., the radula sheath projecting behind and below for 1 mm. Crop large, spherical, constricted 

 longitudinally into two symmetrical halves about 2 mm. long by 3 mm. wide. The sides are ridged 

 laterally by the ec.nver'.;ing muscles to the lower anterior portion, the walls very thick and muscular. 

 I'.asc (if rrcip joined 'ln'<'i-tly to the dorsal portion of the pharyngeal bulb, with no trace of a petiole. 

 I.aliial ilise nMiml, eoiivex, its light brown cuticle radially striated, the opening elongate, slit-like, the 

 ends dilated. The labial armature is made up of a band of mosaic-like plates, about 0.240 mm. in 

 width, incomplete above. Each plate is in the form of a minute erect hook, its apex directed out- 

 ward, either pointed or blunt sometimes bifid (pi. xx, fig. 83). Height of a typical labial element, 

 0.007 nun. At the lower margin of the labial armature (pi. xx, fig. 81) a single flattened i)late-like 

 concave thickening of the cuticle projects freely forward for 0.082 mm., its width 0.033 nun. at the 



