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



Canada, Great Britain, and Norway. Many other forms, both recent and fossil, have 

 been described, ranging as far back as the Cretaceous formations. 



1. Cytheropteron scajilioicles, n. sp. (PL XXXIII. fig. 1, a-d). 



Shell compressed, oblong ; seen from the side, elongated, subtriangular, highest ■ in 

 the middle, the greatest height being nearly equal to half the length ; anterior extremity 

 depressed, narrowly and sharply rounded, posterior produced, much depressed, subacutely 

 pointed ; dorsal margin boldly arched, sloping more steeply behind than in front, ventral 

 gently convex ;• seen from above, the outline is compressed, oblong, obscurely hexagonal, 

 with rounded angles, width scarcely equal to half the length ; sides nearly straight, and 

 converging somewhat abruptly towards the extremities which are subacuminate ; end 

 view depressed, broadly oval, ventral surface indented. Surface of the shell smooth, 

 marked 'Rath a few faint and distant curved longitudinal striae. Length, l-80th of an 

 inch ('325 mm.). 



A few specimens found in a dredging from Balfour Bay, Kerguelen Island, 20 to 50 

 fathoms (Station 149). 



This is not unlike in general character to Cytlieropteron subcircinatum, Sars, but is 

 very much less tumid. 



[PI. XXXIII. fig. 1, a-d. a Carapace seen from left side, h from above, c from 

 below, cZfrom front. Magnified 80 diameters.] 



2. Cytheropteron ivellingtoniense, n. sp. (PL XXXIV. fig. 4, a-d). 



Shell, seen from the side, flexuous in outline, subrhomboidal, highest in the middle, 

 height equal to nearly two-thirds of the length, anterior extremity depressed, rounded 

 ofi", posterior wider, looking obliquely downwards, produced in the middle into a short, 

 broad, and obtuse beak, dorsal margin boldly and evenly rounded, ventral convex, 

 sinuated in front and behind the middle-; seen from above, the outline is subovate, 

 widest behind the middle, where the lateral alae project only very slightly ; from this 

 point the lateral margins slope with a gentle curve towards the anterior extremity, which 

 is obtuse and slightly mucronate, more abruptly and almost in a straight line to the 

 hinder extremity, which is acuminate ; width equal to the height ; the end view is 

 equilaterally triangular, the angles rounded, and the lateral margins rather boldly 

 ■ curved, ventral line nearly straight. The shell is almost smooth, but marked on parts 

 of its surface with closely-set minute puncta, the ventral surface is indented longitudinally 

 along the median line, and bears also a few faint curved strise ; the lateral alae are 

 curved, scarcely angular, and but slightly prominent. Length, l-43d of an inch 

 (•575 mm.). 



Several specimens of this species were found in a dredging from Wellington Harbour, 

 New Zealand. They were taken in the tow-net at trawl, but at what depth is- not 



