— 20 — 



much smaller than in large animais, and the front end of cara- 

 pace shows — as might be expected — a différent shape in such 

 spécimens, while in half-grown animais the lobe and the front 

 part of the carapace have assumed respectively nearly the final 

 size and shape. 



In my former paper I pronounced the opinion that « the 

 Plankton spécimens referred by Ortmann to T. obtusifrons 

 certainly belong to T. vulgaris ». Having now two distinct but 

 closely allied species with latéral denticles on the carapace well 

 developed, it is of course impossible to décide whether the 

 spécimens seen by Ortmann belong to T. vulgaris or to 

 T. œqualis; most probably both species were présent in the 

 material in question. — Some informance on the real T. obtu- 

 sifrons, G. O. S., is given below in « Remarks » on T. vulgaris. 



Thysanopoda vulgaris, H. J. H. 



Thysanopoda vulgaris, H. J. Hansen, Bull. Musée Oce'anogr. 

 n° 3o, p. i5. 



Description. — The front part of the carapace almost as in 

 T. œqualis, but the end has a quite minute conical vertical tooth 

 or at least a vestige of that tooth. The latéral marginal denticles 

 on the carapace near its posterior end are well developed. The 

 lobe from first antennular joint is characteristic; it covers the 

 inner basai part of the upper surface of second joint, the por- 

 tion overlapped being decidedly less than half and almost only 

 i/3 of the length of the joint, and not fully half of its breadth, 

 thus only about 1/6 of its whole upper surface. The lobe is as 

 long as, or a little longer than, broad and somewhat broader at 

 the base than in front; its anterior margin is transverse, a little 

 convex or feebly concave, the front outer angle being either pro- 

 duced into a tiny triangular tooth or rounded; the shape of 

 this anterior margin is, however, often not very easy to make 

 out, because the setae on the surface of the lobe, which are 

 longer than in T. œqualis, proceed beyond the margin named, 

 concealing it to some degree. — As to other particulars on this 

 species I refer to my earlier description. 



