744 DR WALTER E. COLLTNGE. 



tooth-like spine on the anterior inner border ; flagellum with thirteen to fourteen 

 joints. First maxillae (fig. 63) with outer lobe terminating in eleven curved and a 

 single straight spines, inner lobe with three setose spines, and a small curved spine 

 on the outer side distally. The segments of the mesosome (fig. 67), excepting the 

 first, are almost subequal ; the pleural plates of the first are laterally truncate, with 

 the anterior angle pointed. Coxal plates large, occupying the whole of the lateral 

 margins of the -second to seventh segments, gradually increasing in width ; posterior 

 angle of the seventh produced backwardly. Maxillipedcs (fig. 64) with four-jointed 

 palp, no groove on the third joint, basal plate, epipodite, and inner lobe elongated. 

 Thoracic appendages of normal type (figs. 65 and 66). Metasome (fig. 68) has two 

 short segments and sutures indicating a coalesced third, terminal segment long, 

 slightly convex and raised in the mid-dorsal line, sides straight and gradually 

 tapering, lateral angles obtuse, posterior margin medially produced in a blunt rounded 

 process extending beyond the lateral angles. Uropoda (fig. 69) somewhat narrow, 

 endopodite with posterior margin bluntly rounded, anterior margin slightly 

 produced. 



Length of c? 19 mm., of P 15 mm. 



Colour (in alcohol) light brown. 



Geographical Distribution. — At present known only from St Andrews Bay. 



Remarks. — Externally, small examples of this species are not unlike /. viridis 

 (Slabber) ; indeed, I had referred such to that species until meeting with the larger 

 specimens. Later, on examining the minute structure numerous important differ- 

 ences were found. Fortunately, whilst engaged upon this species, Professor G. 0. 

 Sars very kindly sent me examples of /. viridis from ISLorway, and it was at once 

 evident that I had something very different. Large adult males might easily be 

 mistaken at first sight for I. granulosa, Rathke. 



From /. granulosa this species differs in the shape of the cephalon, which is more 

 deeply excavated on the anterior margin, and the posterior lateral portions slope 

 inwards. The antennulse are more slender, as also the antennae, the style of the 

 latter being longer. There are minor differences in the form of the first maxillae and 

 maxillipedes. The coxal plates form the complete lateral margin of the mesosomatic 

 segments 2-7, whereas in /. granulosa those on the second segment occupy the 

 anterior two-thirds and not the whole of the third segment. The segments of the 

 metasome differ in form, especially the terminal one, which has the sides gradually 

 sloping, with the posterior margin truncate laterally and a prominent median tooth. 

 The endopodites of the uropoda are more triangular in shape, being cut away 

 laterally. 



From /. viridis (Slabber) the differences, apart from its greater size, are more 

 striking ; thus it differs in the shape of the cephalon, the antennulae, and the antennae. 

 The style of the antennae is much shorter than in /. viridis. In the form of the first 

 maxillae and in the maxillipedes the differences are more pronounced, especially the 



