DISCODORIS BRANNERI MAC FARLAND 75 



posterior lobe is very much smaller and thinner, and lies trans- 

 versely, its anterior border in contact with the central nervous 

 system. It is somewhat reniform in shape, measuring 0.7 mm. 

 in transverse by 0.3 mm. in longitudinal diameter. 



ALIMENTARY SYSTEM. 



Labial armature. The oral tube is short and conical, i.o 

 mm. in length, bearing a colorless cuticula. The labial armature 

 is small, consisting of a median plate, 0.735 mm. in length by 

 0.135 mm. in greatest width, and of two triangular lateral plates, 

 0.63 mm. in greatest length by 0.3 mm. in width (PI. XIII, fig. 

 66). The median plate is elongate, spear-shaped, and is made up 

 of closely set granular thickenings of the cuticle of varying size. 

 Its median portion is marked by a narrow line in which the 

 thickenings are much less numerous and are smaller than on 

 either side. In the densest regions these granulations may assume 

 the aspect of very short blunt rodlets measuring up to 0.002 mm. 

 in diameter, and approximately the same in height. 



The median plate is set off from the lateral ones by a narrow 

 strip of cuticle, nearly destitute of such elevations. The lateral 

 plates are approximately right angled triangles in general out- 

 lines, the apex being directed backward, the perpendicular side 

 parallel to the median plate. The granular thickenings forming 

 these lateral plates are of the same general type as those of the 

 median one, are very dense in the central portions and merge 

 off gradually toward the periphery into the thickened cuticula sur- 

 rounding them. 



Radula. The pharyngeal bulb is large and strong, 3.0 mm. in 

 length by 2.0 mm. in height, in form truncately conical, the 

 radula sheath projecting very slightly behind and below. The 

 radula is broad, short, and deeply grooved, colorless in front, but 

 becoming straw colored posteriorly. The teeth are in twenty-six 

 rows, the rhachis of the radula is naked, and the pleural teeth 

 vary in number from forty-six in the anterior half rows, to 

 fifty in the posterior ones. The dental formula may be expressed 

 46-50:0:46-50x26. The teeth are all simple hooks in form, the 

 majority except the outermost and innermost in each row, being 

 of the same size and shape (PI. XIII, figs. 67, 68 ; PL XV, fig. 75). 

 The base of a typical average tooth measures 0.082 mm., the height 



