c NATURAL HISTORY BULLETIN. 



ner sides nearly straight, (as in the figure). The adoral 

 shields are very incorrectly figured, the distal lobes being 

 omitted. They are three-lobed; inner lobe is narrowed and 

 tapered to the end; the distal end curves around the oral 

 shield, one lobe touching the first under arm-plate and the 

 other separating the oral shield from the side arm-plate (as 

 in O. ensiferd). The first under arm-plate is small, concave, 

 with a thin, flat, vertical crest, near each inner angle, running- 

 inward and upward and forming part of the rim around the 

 large, exposed, oral tentacle-pore, which is situated in a de- 

 pression of the jaw-margin and gives exit to a large and long 

 tentacle. Teeth four or five, stout; the uppermost longer 

 and conical; the others flat and stout, obtuse. Tooth-papilla 

 two, conical, at the tip of the jaw on the small apex of the 

 dental plate. Mouth-papillae about seven, in a close row, 

 small, spiniform, acute, the outer largest (all nearly as figured). 

 Nearly all are attached to the buccal plate, but the two outer 

 ones stand below the tentacle-pore like tentacle-scales. In 

 some specimens there are two or three similar papillae above 

 the tentacle-pore, within the mouth-slit, (as in O. ensiferd). 



The under arm-plates are quite unlike Lyman's figure. The 

 proximal ones are broad and short shield-shaped, slightly sep- 

 arated by the side plates; the distal edge is evenly curved; 

 the outer angles prominent and acute, the sides much in- 

 curved at the tentacle-pores; the inner end very obtusely 

 angulated. They have two faint diagonal lines crossing 

 them; the outer edge is a little raised and thickened. 



Tentacle-scales two on several joints, flat, ovate-lanceolate, 

 acute. Arm-spines about five; the upper ones on the basal 

 joints long, slender, tapered, acute; the middle ones, on the 

 joints further out, are mostly flattened, with finely serrulate 

 edges (as figured); the lower ones are usually the most 

 slender. The spines are hollow, and glass) 7 when wet. The 

 upper arm-plates are rather small and considerably separated, 

 shaped nearly as in Lyman's figure; they are slightly carinated 

 and the middle field is whitish, so that a pale median line 



