428 MESSES. T. AJyD A. SCOTT— EEVISION OF THE BEITISH COPEPODA 



a few terminal setoe in addition to the apical and marginal 1-jointed branches ; the 

 marginal branch is nineh smaller than the other (PL 37. fig. 21). 



Anterior foot-jaws composed of two large, strongly dilated joints ; the first joint bears 

 tnree marginal processes on the distal half ; the middle process is much smaller than the 

 other two ; the end joint bears two vinequal and moderately short setose spines on the 

 inner edge and two elongate subequal spiniform claws and a few setse at the extremity 

 (PI. 37. fig. 38). 



Posterior foot-jaws elongate, moderately stout, tapering towards the distal end ; a long 

 plumose seta springs from near the end of the first joint ; the second joint is strongly 

 ciliate on the upper margin, while the last joint bears two subterminal plumose spines 

 and one long and one short terminal seta, as shown in the figure (PL 37. fig. 52). 



The first four pairs of swimming-feet are robust ; the interior marginal setse on both 

 branches are stout and strongly plumose, while the exterior margins are fringed with 

 small sj)ines ; the outer marginal spines of the outer branches and the spiniform terminal 

 setse of both outer and inner branches are stout, and strongly setose on the exterior 

 edges ; a stout spine springs from the interior distal angle of the second basal joint of the 

 first pair (PL 38. figs. 10 & 22). 



The fifth pair are sub quadrangular in outline ; the produced inner portion of the basal 

 joint is cylindrical and twice as long as broad ; its extremity is somewhat bilobed, and 

 reaches to near the end of the secondary joint ; the inner mai'gin bears several small setse ; 

 each of the terminal lobes forms the base of a spine, the inner one of which is stouter and 

 more elongate than the other ; the secondary joints are subquadrate, but rather longer 

 than broad, and terminate in three unequal lobes, each of which is the base of a 

 moderately stout spine, and is fu.rnished Avitli three apical spine-like teeth ; the middle 

 one of the three spines is longer than the one on either side ; there are a few spine-like 

 teeth on the lateral aspect of the basal joint, as shown in the figure (PL 38. fig. 32). 



Caudal stylets short and moderately stout (PL 38. fig. 51). 



Habitat. All roimd the British coasts ; moderately common. 



Remarhs. This species is readily distinguished from the other Ectinosomata by the 

 form of the animal, and the structvire and armature of the swimming-feet. 



EcTiNOSOMA PKOPiNQUUM, sp. n. (PL 36. figs. 19, 27, 46 ; PL 37. figs. 2, 15, 32, 55 ; 

 PL 38. figs. 9, 23, 34, 54.) 



Description. Length 1"1 mm. (2^ of an inch). Body seen from the side fusiform ; 

 rostrum prominent and projecting nearly straight forAvard, somewhat spoon-shaped, or 

 with the sides slightly decurved and the apex rotm^ded. 



Antennules short, stout, strongly setiferous, and composed of five joints. The pro- 

 portional lengths of the joints are nearly as shown by the formula : — 



No. of the joints : 1.2.3.4.5 



Proportional lengths : 11 9 12 7 12 



Antennte nearly as in Ectinosoma Sarsi (PL 37. fig. 2). Mandibles also somewhat 

 similar to those of that species (PL 37. fig, 15), but two of the terminal setae of the 

 apical branch of the palp are united for a short distance at the base. 



