IMPERFECTLl -KNOWN OSTEACODA. 187 



beak, but with a shallow antennal notch just in front of the ventral margin, posterior 

 margin broadly and evenly rounded ; dorsal and ventral margins boldly and evenly 

 arcuate : seen from above the outline (PI. XXI. fig. 2) is regularly ovate, twice as long 

 as broad, greatest width in the middle. Shell chitinous, smooth, its edges above and 

 below the antennal notch bordered with a thin chitinous flange, within which is a 

 nodulated crest having an appearance somewhat like the corneal lenses of an insect-eye 

 (fig. 3). Length 1 mm. The antennte are of the normal type, but with the first joint 

 smaller than usual (fig. 4) ; caudal laminse (fig. 5) narrow ; at the proximal end three 

 small ungues, followed by one larger, then three small and one larger, one small and 

 two very much larger terminal claws. 



Hab. Trincomali, Ceylon. Three specimens, d . 



Genus Cypridinodes, gen. nov. 



Like Cypridina, except as to the three pairs of maxillae. The first pair (PI. XXII. 

 fig. 26) form a simple, elongated, triarticulate limb, which bears at its distal extremity 

 several strongly pectinated claws and setse ; to the basal joint is attached a small single- 

 jointed trisetose palp. The second maxilla (fig. 27) is in general build like that of 

 Philomedes or Cypridina, but the principal masticating processes are armed with blunt 

 nodular marginal teeth (fig. 27, a-c) ; third maxilla (fig. 28) without the hatchet- 

 shaped lobe of Cypridina, which is replaced by a digitiform prolongation, retaining, 

 however, something of the hatchet-shape. 



Cypridinodes favus, sp. nov. (Plate XXII. figs. 20-3L) 



Shell of the female seen from the side (fig. 20) broadly subovate, width equal to 

 nearly three-fourths of the length ; anterior extremity rectangularly truncated, posterior 

 produced into a broad, truncated, subconical beak ; dorsal and ventral margins boldly 

 arched: seen from above (fig. 21) the outline is irregularly hexagonal, greatest width 

 in the middle, and equal to two-thirds of the length ; extremities wide and truncated, 

 the anterior broadly mucronate, the posterior irregularly notched ; lateral margins 

 deeply furrowed in the middle, thence sloping steeply in a sinuous line to each 

 extremity. Surface of the valves coarsely pitted with deep irregularly-angular 

 impressions, and raised into two subcentral mammilliform elevations, between which 

 is a deep transverse furrow ; a little within, and parallel with, the ventral margins the 

 central portion of the valve is bounded by an irregular jagged crest ; the left valve is 

 overlapped by the right in front and on the dorsal aspect. Length 3 mm. The 

 penultimate joint of the antennule (fig. 22) has at its distal end a stout ringed seta, 

 which bears a series of about twelve stout lash-like setse arranged in a secund manner 

 along its inner edge ; two of the principal setse of the terminal joint are dilated at 

 their bases, forming a pair of globular or subglobular sacs ; first seta of the swimming- 



YOL. XVI. — PART IV. No. 1.— April, 1902. 2 f 



