RECENT BRITISH OSTRACODA. 



^69 



bearing long plumose seta3, secondary branch short and, in the male, prehensile. Man- 

 dibles distinct, narrow, dentate at the apex : palp large, pediform, geniculate, four-jointed ; 

 basal joint very large, produced at the base into a dentate process which stretches beyond 

 the apex of the mandible, last joint armed with elongated claws. Two pairs of jaws ; 

 first pair composed of three lobes, the external lobe or palp large, biarticulate, and 

 incurved ; second pair provided with a small branchial plate and an elongated suljpedi- 

 form palp. Two pairs of feet ; first pair elongated, five-jointed, bearing at the base, like 

 the second maxillse, a small branchial plate, dissimilar in the male and female ; second 

 pair very small and rudimentary. Postabdomen forming two short clawed laminte." 



I have had no opportunity of properly examining any of the animals belonging to this 

 family ; and, indeed, its sole claim to admission here rests at present on a single individual 

 taken in Shetland by the Rev. A. M. Norman. The definition given above is taken from 

 the work of G. O. Sars, who describes three species of Conchoecia, which appear to be 

 not uncommon on the Norwegian coast, where they are met with either in great depths 

 of water (100-300 fathoms) or swimming near the surface in the open sea. 



Genus Conchcecia, Dana, 



" Valves elongated, produced in front into a beaked process ; shell finely reticulated or 

 marked with concentric stria? ; very slightly pilose. Dorsal surface of the carapace flat- 

 tened in front, sometimes slightly excavated and keeled. Upper antennae in the female 

 small, scarcely protruding beyond the shell, immobile, obscurely articulated, bearing at 

 the apex four large auditory cilia and a seta twice as large, curved upwards and finely 

 denticulated ; in the male much larger, distinctly four-jointed and moveable, some of the 

 apical setse much elongated, and dififering in structure from those of the female. Lower 

 antennge very powerful, basal portion elongate-triangular, and nearly equalling half the 

 length of the shell ; natatory branch seven- to eight -jointed ; first joint longer than the 

 rest united, secondary branch biarticulate, first joint much dilated, last very small, 

 bearing, in the female, several subequal setae, in the male a short hook-like claw. La- 

 brum large, produced like a hood. Mandibles armed at the lower extremity with a 

 strong tooth and a semicircular, flexuous, and finely toothed crest : palp robust, scarcely 

 projecting beyond the valves ; basal joint bearing near the apex, in lieu of a branchial 

 appendage, a densely ciliated seta ; last joint obliquely truncate, armed with two long 

 and finely toothed claws or spines. Pirst pair of jaws composed of two strongly spined 

 incisive lobes and a large palp, the first joint of which is subovate, and set with long 

 setae on the anterior and posterior margins ; the last small, incurved, armed with several 

 curved claws, which increase in length inwardly. Incisive part of the second pair of 

 jaws scarcely lobed, strongly spined at the apex ; branchial lamina small, three-lobed ; 

 palp elongated and directed forwards, three-jointed, last joint very small and armed with 

 three unequal claws. First pair of feet five-jointed, bearing at the base a three-lobed 

 branchial plate as in the second pair of jaws ; in the female narrow, directed forwards, 

 and armed at the extremity with three elongated claws ; in the male much stronger and 

 stretched backwards, terminated by three very long ciliated setae, which are curved 



