1909.] FROM THE BAY OF BISCAY. 853 



and development, the specimens are in absolute agreement on 

 every point. 



The mouth-parts are figured afresh, Buchholz's figures and 

 descriptions not being accurate. In my opinion a great many 

 inaccuracies arise from the custom some authors have of mount- 

 ing their specimens before describing or figuring them. This 

 appears to be a case in point. I could not at first discover how 

 Buchholz could possibly have overlooked the molar (which, small 

 and degraded as it is, can be plainly seen under the 1 in. obj.), 

 until I tried placing the mandible in the position represented by 

 him and mounting it. The exact effect of his figure was 

 immediately obtained, through the weight of the cover-glass 

 flattening and depressing the delicate pellucid molar ridge to 

 such an extent as to render it indistinguishable from the body 

 of the mandible. 



Side-plates, — The hind margin of the fii'st three side-plates is 

 entire with 3 or 4 setules inset, and a single denticle at the 

 inferior angle, not 3 sharp teeth as described by Buchholz who 

 apparently mistook the insertions of the setules for incisions of 

 the mai'gin. 



Head (fig. 1). — Lateral corners more pointed in Buchholz's 

 specimen . 



Antennce. Sujjerior. — 1st and 2nd joints of the peduncle sub- 

 equal ; 3rd joint half the length of the 2nd. In Sars's specimen 

 the 1st joint equals in length the 2nd and 3rd combined. The 

 first two joints carry extremely fine ciliated hairs. Primary 

 flagellum. — Buchholz gives 15-16 joints; Sars, "12 articulations 

 only." Buchholz's co-type had 12 joints, Sars's, 13 joints. The 

 1st joint of the flagellum is shorter than the 2nd. All the joints 

 carry delicate setae, with long thread-like tips, and in addition 

 to these setse, the alternate joints beginning with the 2nd are 

 each provided with a very long, hyaline sensory filament, inset on 

 the inner surface in a line with the accessory flagellum. The 

 accessory flagellum (fig. 2) is pi-esent in both co-types, but quite 

 rudimentary and microscopic in size. It consists of a minute 

 pellucid flat joint carrying one ciliated hair and one long thread- 

 tipped seta. I have found this microscopic accessory flagellum in 

 all the other members of the family I have examined, distinct in 

 Sympleustes latipes, but too small to be of any value in classi- 

 fication in the others. 



Ivferior. — The proportions of the peduncle joints are as given 

 by both authors, but the peduncle is longer in proportion to the 

 flagellum in Buchholz's specimen. Flagellum 6-jointed. 



Oral parts. — Upper lip unequally bilobed, incision oblique. 



Loioer lip. — Outer lobes veiy large and rounded ; inner lobes 

 not projecting. Both lips covered with fine downy hair; the 

 outer lobes of the lower lip each with a cluster of 5 or 6 stronger 

 hairs. 



Mandibles (figs. 3 & 4). — The anterior portion of the man- 

 dibles forms a scoop-like projection, almost triangular, with the 



58* 



