462 



MR. G. S. BRADY'S MONOGRAPH OF 



Section II. MYODOCOPA, G. O. Sars. 

 Pam. 1. Cypridinid^, Baird. 



SheU mostly hard and compact in structure, smooth or punctate, and sometimes beset 

 with short hairs, notched at the antero-inferior angle, so that when the valves are closed 

 there remains still a large aperture for the protrusion of the lower antennae. Upper 

 antennae large, geniculated at the base, many-jointed, and bearing, especially towards 

 the apex, several long ringed setae. Basal portion of the lower antennae broadly trian- 

 gular, bearing a slender secondary branch, which is set with a few short setae, and a 

 large natatory branch, which is mostly nine-jointed, and bears several long ciliated setae. 

 Mandibles rudimentary, the palp very large, geniculated, pediform, four-jointed; first 

 joint large and thick, bearing at the apex a slightly setose appendage, like a rudimentary 

 branchial plate; last joint very short and strongly clawed. Three pairs of jaws, some- 

 what pediform. Pirst pair of jaws having four spinous lobes, the exterior or largest 

 biarticulate ; first joint large, elongated, subquadrangular ; last very short, and set with 

 numerous spines or claws. Second pair of jaws short and stout, composed of several 

 setose or unguiculate segments; the exterior short, three-lobed, and beset with short 

 finely ciliated setae, bearing at the base a very large semilunar branchial plate, which 

 is provided with numerous marginal setae. Third pair of jaws smaller, composed of 

 three spinous lobes, beneath which is a membranous subovate plate, beset with many 

 finely ciliated setae ; one pair of feet, forming a very long, flexuous, subcylindrical annu- 

 lose body, which is armed towards the apex with long prickly spines. Postabdomen 

 large, composed of two broad closely appressed laminae which are armed posteriorly with 

 strong marginal claws. Two compound pedunculated eyes, between which is a large 

 simple eye, and at its base a short cylindrical tentacle. Male of less height than the 

 female ; eyes more developed ; copulative organs of complex structure. Ova and em- 

 bryos borne beneath the shell of the female. 



The foregoing description of this family is adopted, with very slight alteration, from 

 the definition of G. O. Sars. The Cypridinidae are comparatively scarce in the seas of 

 temperate latitudes, but much more abundant in the tropics, constituting, indeed, a not 

 unimportant part of the phosphorescent agencies there so strikingly developed. Many 

 species and genera have been described by various authors, but, except in a few cases, 

 their anatomical structure has not been thoroughly investigated. 



In the British seas the few species which have hitherto been discovered are taken 

 mostly by the use of the towing-net at night. Some have occurred amongst dredged 

 sand, and some have been taken by the hand-net amongst Zostera in tide-pools ; but 

 this seems to be an exceptional circumstance. The animals are essentially of natatory 

 character, their powerful antennae having free play, even when the valves are quite 

 closed, through the large aperture which is characteristic of the family. 



Genus 1. Philomedes, Lilljeborg. 



Valves elongated, thin ; notch broad, anterior extremity obtuse. Upper antennae six- 

 jointed, scarcely attenuated at the apex ; antepenultimate joint bearing a stout seta. 



