of the Fishery Board for Scotland. 217 



This form — Nogagus latus — has a close general resemblance to 

 Caligus, except that the frontal plates are without lunulce. The cephalic 

 shield is sub-rotundate, being nearly as broad as it is long, and it is also 

 nearly equal to two-thirds of the entire length of the animal. The fourth and 

 fifth thoracic segments are short but of moderate width ; the last is about 

 twice the length of the preceding segment and is sub-quadrate in outline. 

 The urosome is small and appears to be composed of two segments. The 

 furcal joints are also short and broad, while the apical set ae have the 

 appearance of small lamelliform plates fringed with delicate hairs (fig. 1). 



The antennules are moderately stout, and the first joint is furnished 

 with a number of short and stout plumose bristles round the distal end, 

 but the second joint is smaller and bears a few apical spines (fig. 2). 



The second antennules are also stout, and they are each armed with a 

 strong terminal claw (fig. 3). 



The first pair of maxillipeds are considerably elongated and resemble 

 nearly the same appendages in Nogagus borealis, Stp. and Ltk. (fig. 4). 



The second maxillipeds are short and very robust, their distal end is 

 moderately truncate, and they are each armed with a short but strong 

 terminal claw (fig. 5). 



The first pair of thoracic feet have both branches short, sub-equal, and 

 two-jointed ; each branch is provided with three stout and moderately 

 elongated terminal setae, the outer branch having also a few short spines 

 on the exterior margin, as shown in the drawing (fig. 6). 



The second pair is rather more robust than the first, both branches 

 being two-jointed and of nearly equal length. The first joint of the inner 

 branch has one plumose seta on the inner margin, while the second bears 

 seven or eight similar setae round its distal end. The first joint of the 

 outer branch is also furnished with a seta on the inner margin and a 

 small spine on the outer distal angle, but the end joint carries five setae 

 round the inner margin and apex and four spines on the exterior edge 



(% 7). 



The third pair, which, like the first and second, has both branches 

 bi articulated, is also moderately stout, but the branches, though armed 

 nearly as in the second pair, are rather shorter (fig. 8). 



The structure of the fourth pair is similar to that of the other three, 

 but this pair is rather smaller, and both branches are very short. One 

 seta springs from the inner distal angle of the first joint of the inner 

 branch, while the second joint carries three or four round the distal end. 

 The first joint of the outer branch is provided with a small spine 

 exteriorly, while the end joint has five setae round the inner margin and 

 apex, and three or four small spines on the outer margin (fig. 9). 



Habitat. — On piked dog-fish (Squalus acanthius) captured in the 

 North Sea in 1902. 



Nogagus ambiguus, sp. n. PI. xv., figs. 10-17 (tf) 



In this species the cephalic shield is of an oval outline, and the lateral 

 margins where they meet anteriorly form a more or less distinctly angular 

 instead of a broadly rounded front, as in the form just described. The 

 last two thoracic segments are of nearly equal size, and their width is 

 about one-third of that of the cephalic shield at its widest part. The 

 urosome (abdomen) consists of one small segment, and the furcal joints, 

 which are also very short, are each furnished with moderately long 

 plumose setae (fig. 10). 



The antennules, which are of average size, are also adorned with long 

 plumose setae (fig. 11). 



