— i3 — 



b. Carapace without any dorsal spine behind the rostrum 

 and without any latéral marginal denticles in front of 

 the middle (only the pair near the posterior end being 

 présent). 



a. Fourth and fifth abdominal segments each with a 



dorsal spine from the posterior margin 



2. T. bïproducta Ortm. 



g. Third abdominal segment (but none of the following 

 segments) with a dorsal spine from the posterior 

 margin 3. T. monacantha Ortm. 



y. None of the abdominal segments with dorsal spines. 



f. Basai joint of the antennulae will a very conspi- 

 cuous spine proceeding forwards from the upper 



distal margin near the inner side 



4. T. microphthalma G. O. Sars. 



f f . Basai joint of the antennulae without any spine 



from the upper distal margin 



5. T. vulgaris, n. sp. 



B. Carapace without latéral marginal denticles. 



a. Carapace without any transverse gastro-hepatic groove. 

 Maxillulœ have the palp short, situated along the outer 

 margin of the lobe from the preceding (third) joint and 

 not reaching beyond its end; the exterior plate from the 

 lobe of first joint (1) is exceedingly large, its major part 

 proceeding outside the outer margin of the joints of the 

 appendage. The eye-stalks without any tubercle. 



a. Second joint of the antennular peduncle without 

 any terminal dorsal spine. No ridge or impressed 

 longitudinal line somewhat above the latéral margin 

 of the carapace. Abdominal segments without any 

 dorsal spine. 



(1) This interpretion is explained on page 21. 



