of the North Atlantic and of North-Western Europe. 683 



male there are three long, but unequal setse, and two much shorter sensory 

 filaments ; the proximal seta much the longest, and armed in a part of its length 

 with more or less numerous minute marginal spines or hooks. Secondary branch 

 of the antenna bearing, on the basal joint a marginal, nipple-shaped prominence ; 

 natatory setae scarcely longer than the peduncle, slightly dilated, and lancet- 

 shaped towards their apices. Basal joint of the mandible palp elongated, and 

 usually as long as, or longer than the united lengths of the three following 

 joints. Second maxilla much shorter than the first foot which, in the male, is 

 very large and ends in a lash of three equally long setae. 



Many species belonging to this sub-family we have had no opportunity of 

 examining ; in such cases we have simply given descriptions condensed from those 

 of Professors Claus and G. 0. Sars. We are, however, much indebted to both 

 of those authors for their kindness va su]Dplying us with examples of several of 

 the species described by them. 



Genus 1. CoNCHCECiA, Dana, ex. jd. 



Shell elongated, subquadrangular, posterior extremity truncated, sometimes 

 smooth, but usually ornamented with a striated or reticulated sculpture either 

 towards the margins or over the general surface of the shell ; rostrum and sub- 

 rostral sinus well developed ; hinge processes absent or only feebly develo^jed. 

 " A group of club-shaped gland sacs near the posterior end of the dorsal margin, 

 another group at the upper angle of the posterior margin of each valve, and a 

 third at the infero-posteal angle of the right valve." AntenniJes of the female 

 slender, cylindrical, bearing four sensory tubular filaments, and one long, slender 

 seta, those of the male with three equal elongated setae, and two unequal sensory 

 filaments. Antennae greatly developed, basal portion very large, j)yi'iform, elon- 

 gated, natatory branch 7- 8- jointed, first joint elongated, the rest very short ; 

 secondary branch two-jointed, basal joint forming a flattened expansion, last 

 joint short and bearing in the female a lash of filaments, and in the male an 

 additional falcate process. Labrum hood-like, with irregular processes in front. 

 Labium bilobed, inner margins of lobes setiferous. Basal joint of the mandible- 

 palp as large as, or larger than the remainder of the limb (Plate xvi., fig 17) 

 bearing at the apex a single stout plumose seta ; last joint with three ciliated 

 spines on the inner margin. First pair of maxillae (fig. 18) composed of two 

 masticatory lobes, with a large two-jointed palp which is armed with several 

 curved spines. Second pair of maxillae pediform (fig. 19) composed of a simple pre- 

 hensile process, together with a three- jointed palp which terminates in three unequal 

 curved claws. First pair of feet elongated, five-jointed ; in the female directed 

 downwards, apical portion like the palp of the second maxilla; in the male 



