1909.] FROM THE BAY OF BISCAY. 859 



and 2nd are small ; the 3rd is considerably longer, but not much 

 wider than the 2nd ; and the 4th is the largest, inferior margin 

 strongly curved, hind margin only a little concave (fig. 19). 



Head nearly as long as the first two perteonal segments ; 

 rostrum very small, recurved, more so in the female than in the 

 male ; lateral coi'ners truncate, not much produced ; post-antennal 

 corners small and rounded. 



Eyes large, oval ; quite colourless in spirit specimens, and 

 difficult to trace though they show clearly enough in photographs of 

 the animal. Walker's statement, " eyes wanting," is not correct. 



Antennce. — Superior antennce over two-thirds the length of 

 the body, but the proportion varies with the age of the animal. 

 Peduncle : 1st joint stout, as long as the 2nd and 3rd together ; 

 3rd joint shorter and much more slender than the 2nd ; in the 

 young female 5"5 mm. long, and in Chevreux's first description the 

 3rd joint is only half the length of the 2nd. The peduncle carries 

 some fine hyaline hairs, as well as 3 or 4 ciliated ones, but the 

 construction of these and of the filaments and setae of the 

 flagellum is exceedingly difiicult to observe, even when magnified 

 500 times, because of their fragility aiid transparency ; this 

 probably accounts for Chevreux's description " presque absolument 

 glabres." Primary fiagellum. — All the flagella of the larger 

 specimens were unfortunately broken, 34 joints remaining on one; 

 1st joint almost double the length of the 3rd joint of the 

 peduncle, carrying 3 or 4 clusters of sensory filaments ; the 10 

 succeeding joints short, each with a cluster of filaments ; the 

 remaining joints longer and thinner, provided each with small 

 setfe, and a. long sensory filament. The rudimentary accessory 

 flagelluin is cha.racteristic of the family ; it consists of one minute, 

 pellucid joint, flat and leaf-like, tipped with 2 or 3 hyaline cleft 

 setfe (fig. 18). 



Inferior antennce much shorter than the superior. Peduncle : 

 antennal cone large ; 5th joint about one-sixth shorter than the 

 4th. This proportion appears constant, being the same in all 

 the specimens examined ; Ohevreux in his second account has 

 " beaucoup plus court " instead of the more correct " un pen plus 

 covirt " of the original description. Fiagellum in the young female 

 with 14 joints ; both flagella broken in the large female and in 

 the males, 15 joints remaining in young male. 



Oral jKirts. — Upper lip (fig. 20) : Alike in both sexes. Apex 

 unevenly bilobed, with the rather oblique incision characteristic 

 of the genus ; inner margin of the right lobe minutely crenate. 



Lower lip (figs. 21, 22, and 23). — Inner lobes much broader 

 than the outer lobes ; a figure (fig. 23) is given to show the 

 proportions as seen from above. In the older specimens the lip 

 is flatter and the inner lobes larger in proportion to the outer 

 ones than in the young animal. Sars gives as a generic character 

 " posterior lip with the inner lobes scarcely projecting," while 

 Chevreux has " levre posterieure simple, sans lobes internes." In 

 the young animal the lower lip has a tendency to cuil in on 



