84 THE VOYAGE OF H.M.S. CHALLENGER. 



Opercular scales ; dorsal scales 0"48 mm. high, 0*2 mm. broad ; ventral 0"29 mm. 

 high, 0'12 mm. broad at the base. 



Scales of the coenenchj^ma irregularly polygonal or oval ; height to breadth — 

 0-12-0-1; 0-12-0-06; 0-12-0-1; 0-22-0-15; 016-014 ; 0-16-0-16 mm. 



Habitat. — Station 320, off Monte Video ; depth, 600 fathoms ; bottom, green sand. 



[Magellan Straits, 42 fathoms; rock ("Gazelle").] 



2. Pvimnoella murrayi, n. sp. (PI. XVIII. figs. 3, 3a; PI. XXI. fig. 11). 



In habit resembling the foregoing, but may be distinguished at the first glance by 

 the fact that each dorsal calyx scale bears a blunt spine. The slender little stem rises 

 from a flat, expanded root, which has grown amidst a colony of Polyzoa, its apex is 

 broken off at a height of 50 mm. The axis is relatively stout at the base, 0"5 mm., 

 but soon diminishes to the thinness of a thread, yet it i-emains brittle and is but little 

 flexible throughout its entire course. It exhibits eight longitudinal furrows, corre- 

 sponding to the boundaries of the eight longitudinal canals, its colour is horny yellow. 

 On the stem the polyps form close whorls of six to eight, the first whorl with eight 

 polyps commences at 9 '5 mm. above the root. The calyces, 3 mm. long and 1 mm. in 

 diameter, appear somewhat thickened towards the oral region and are uniformly bent 

 towards the stem. The internodes between the whorls are in this case visible, in that 

 the apices of the cells do not reach the base of the next whorl. The calyces are covered 

 with large scales, which lie over one another in eight to nine rows. Three longitudinal 

 rows of dorsal scales are visible. The broad dorsal scales, covered with little promin- 

 ences, after the first third of the calyx, become strongly convex and develop a median 

 keel which is produced into a grooved spine, and when the calyx is bent stands out 

 towards the circumference. Towards the mouth of the calyx the spines increase slightly 

 in size. The ventral scales are small, smooth and flat, separated in the ventral line by 

 a membranous interspace. The opercular scales are short and broad, lancet-shaped, and 

 cover the mouth like a flap. The mouth appears tnincated. The ventral opercular 

 scales'are not covered by the lateral ones. 



Calj'x scales strongly convex, the lateral edges drawn out, in the three or four 

 upper rows the upper edge runs out into a blunt point, sometimes slightly serrate at 

 the end ; the lower edge is strongly convex, with unsymmetrically distributed teeth. 

 Uppermost row, length to breadth, 0'6— 0"54 mm.; second row 0'4— 0"55 mm. Lower 

 row without spines, 0-4— 0"54 mm. Opercular scales ; dorsal scales, broad, triangulai- 

 0'45-0'53 mm. ; lateral scales 0'54— 0"17 mm. ; ventral scales 0"25— 0"09 mm. 

 Spicules of the coenenchyma, unequal four-sided or three-sided plates, 0"4— 0*3 and 

 0-4-02 mm. 



Habitat. — Station 320, off Monte Video; depth, 600 fathoms; bottom, green mud. 



