74 



OPISTHOBRANCHIATA OF BRAZIL 



mantle edge. The edges of the foot are thin and crenulate. Its 

 color is in general the same as that of the under surface of the 

 mantle. 



Head. The head is inconspicuous, the mouth a vertical slit, 

 bearing upon either side long slender finger-like oral tentacles, 

 1.5 mm. in length, their tips blunt and curving forward. 



Rhinophores. The rhinophores are brownish black, deeply 

 retractile within conspicuous sheaths, with high tuberculate 

 margins, the tubercules being of the same type as those of the 

 general dorsal area. The sheaths reach a height of i.o mm., 

 the whole slightly retracted rhinophore has a height of 2.5 mm. 

 The clavus is of the usual club shape, perfoliate, with ca. 25 leaves 

 on each side. The dark pigment is especially concentrated on 

 the strong stalk of the rhinophore, where it forms a circular 

 band, immediately below the clavus. 



Branchiae. The branchiae are six in number, bipinnate, 

 completely retractile into the branchial pocket, which bears a 

 conspicuous lobulate margin, the low divisions of which carry 

 tubercules similar to those of the dorsum. The anal and renal 

 openings are situated as usual within the circle of the branchiae. 

 The reproductive openings in the specimen were very small and 

 inconspicuous. 



Dimensions. Total length of the whole animal 20.0 mm., 

 its width 14.5 mm., and maximum height 5.0 mm. Length of 

 the foot 16.5 mm., its width 6.0 mm.; greatest width of the 

 mantle margin 6.0 mm. 



INTERNAL ANATOMY. 



Blood Glands. The dorsal integument is rather soft and 

 not thick. The pseudo-peritoneum is colorless, save in the region 

 of the central nervous system where it is thickly sprinkled with 

 minute, dark brown spots. The phagocytic blood glands, two 

 in number lie directly in contact with the central nervous system ; 

 the anterior larger one is elliptical in outline and rather thick, 

 measuring 1.5 mm. in length by i.o mm. in width and 0.2 mm. in 

 thickness, and is dark gray in color, being sprinkled with minute 

 black spots. Its dorsal surface is arched, the ventral concave, 

 while the general contour is smooth throughout. It lies directly 

 in front of the cerebral ganglia upon the pharyngeal bulb. The 



