IMPERFEOTLT-KNOWN SPECIES OF OSTEACODA. 445 



forming a steep curve above the middle, below the middle well rounded and broken up 

 into a series of short blunt teeth ; posterior extremity irregularly emarginate, narrowed 

 and wedge-shaped, most prominent below the middle ; dorsal margin slightly sloping 

 from before backward, and broken into an irregular jagged line ; ventral almost 

 straight, with an upward bend behind. Seen from above, the outline is compressed, 

 subovate, more than twice as long as broad, the whole circumference excessively 

 jagged and uneven, tapered at the extremities, which are obtuse, deeply emarginate in 

 front ; surface covered with large irregularly-rounded nodules, and beset with coarse, 

 rigid hairs. A large polished tubercle over the anterior hinge; hingement of two 

 terminal teeth on the right corresponding with depressions on the left valve. Length 

 1-1 mm. Shell of the female shorter and more tumid. Antennules (figs. 18, 19) six- 

 jointed, the last three joints bearing each tliree or four sette, each of which is about as 

 long as the last four joints of the antennule ; the second and third joints have one seta 

 each, the first none ; the last joint of the antenna (fig. 20) is small, and bears a long, slender 

 unguis with two setse ; the penultimate joint has three fascicles of long setae, and, near 

 its base, a brush of small, short hairs ; second joint small, bearing a single long seta 

 and a few small hairs ; first joint (in the female) with a short, strongly-curved, urticating 

 seta — none in the male. Mandible wide and many-toothed ; palp (fig. 3) four-jointed, 

 its last joint rather shorter and much more slender than the preceding ; branchial plate 

 (fig. 21) five-rayed ; praecrural appendages (fig. 25) elongated, quadrilateral, apices 

 rectangularly truncate, and bearing numerous very fine long hairs; legs similar to 

 those of the Cytheridse generally (figs. 22-24), their terminal claws very long, slender, 

 and moderately curved ; the second joint of the last leg in the male (fig. 24) bears four 

 small, but dense, fascicles of hairs ; that of the female (fig. 4) has only one. Post- 

 abdomen in the female (fig. 5) forming two trisetose lobes. 



Hab. Dredged abundantly in Lyttelton Harbour, depth 1-5 fathoms. 



This species was first described from specimens (shells only) taken during the cruise 

 of the ' Challenger ' in various depths, down as far as 40 fathoms : the localities were 

 East Moncceur Island, Bass's Straits ; Inland Sea, Japan ; and Wellington Harbour, 

 New Zealand. The very long and slender setae of the antennules — as long as those of 

 many Cypridse [Bairdia, Macrocypris, Paracypris, &c.) — seem to entitle this species to 

 a separate generic position, and further distinctive characters are found in the 

 peculiarities of the mandibular branchial plate, the urticating antennal setse, and 

 the setose armature of the third pair of legs in the male. 



VOL. XIV. — PART VIII. No. 3. — Dccemher, 1898. 3 ^ 



