] 74 COPEPODA. 



five stout setae, one near the distal end of the outer margin, 

 three on the truncate apex, and one on the inner margin, as 

 shown in the figure. 



The furcal joints are very short. 



The male does not differ greatly from the female except in 

 the following particulars : The antennules are modified for 

 grasping (PI. XXI. fig. 5). The outer branches of the 

 second pair of thoracic feet are armed with stronger spines 

 than the same pair in the female, while the inner branches 

 are only two-jointed and armed with a stout and claw-like 

 terminal spine (PI. XVI. fig. 9). The fifth pair are some- 

 what smaller than those of the female, and the inner and 

 broadly-rounded portion of the basal joint bears only two 

 apical spines (PL XIV. fig. 10). 



Remarks. Vallentinia ornata was moderately frequent in 

 some of the gatherings, and especially in those from the coast of 

 Devon . Specimens recently collected were easily recognized 

 by their peculiar colour, which was for the most part of a 

 uniform yellow or, in some examples, yellowish-grey ; but 

 that which rendered the specimens so conspicuous was the 

 band of a fine purple colour which adorned the posterior 

 portion of the cephalic segment; this band, which covers about 

 a third of the entire length of the segment, does not extend 

 all the way across but terminates on each side a short distance 

 from the margin ; moreover, the posterior edge of the band 

 is even and coincides with the edge of the cephalic segment, 

 but the anterior edge is deeply crenulated, as shown in the 

 drawing (PI. XIX. fig. 2). Immersion in methylated spirit 

 speedily destroys the purple colour, but it remains intact for a 

 considerable time if the specimens be preserved in formalin. 



Habitat. Mouth of the River Yealm, August 1889. Fowey, 

 Cornwall, between tide-marks ; and New Grimsby Harbour, 

 Scilly Islands, May 1903. Plymouth Sound, vicinity of 

 Chequer Buoy, and Mill Bay, Plymouth, in August ; and at 

 Salcombe in September of the same year. 



MEGARTHRUM *, nov. gen. 



Female. Body considerably dilated and depressed; cephalic 

 segment large and expanded ; rostrum small, deflexed ; the 

 next three segments also expanded, and each narrower and 

 shorter than the preceding one; abdomen moderately stout, but 

 narrower and shorter than the cephalothorax. Antennules 

 short and composed of six or seven joints. Antennae with outer 

 ramus of moderate length and Inarticulate. Mandibles com- 



* fipflpnv, i. e. big joint, with reference to the basal joint of the inner 

 branch of the first feet. 



