4. Thysanopoda vulgaris, n. sp. 



Thysanopoda obtusifrons Ortmann, op. cit. p. 9. [not 

 T. obtusifrons, G. O. S.] 



Description. — This species is closely allied to T. obtu- 

 sifrons, G. O. Sars, but differs in four features. The most 

 important of thèse points is that in T. vulgaris the carapace 

 has a latéral marginal denticle rather near the posterior end, 

 while the margin is smooth in T. obtusifrons. In T. vulgaris 

 the front part of the upper side of carapace is adorned with 

 a low keel reaching nearly to the anterior end, and at each 

 side along the anterior half of this keel we find a rather 

 shallow nearly linear excavation ; the front tip of the carapace 

 is, seen from above, scarcely as obtuse as in T. obtusifrons ; 

 seen from the side the upper margin of the front portion is 

 horizontal, bearing on the end a quite minute conical tooth 

 directed upwards; in T. obtusifrons, seen from the side, this 

 front portion is not horizontal but rounded off and without 

 any tooth (Sars, Pl. xvm. fig. 1). (In half-grown and still 

 smaller spécimens the frontal tooth is directed forwards). 

 A gastro-hepatic groove is wanting, as in T. obtusifrons, T.pec- 

 tinata, T. distinguenda and T. lateralis. The eyes are rather 

 small and black with a brownish hue. As in T. obtusifrons 

 the basai joint of the antennular peduncle shows a lobe covering 

 the proximal inner half of the dorsal side of second joint, but 

 this lobe is narrower and its front margin more rounded than 

 in T. obtusifrons (Sars, Pl. xvm. fig. 2). In T. vulgaris the 

 endopod of the uropods protrudes slightly beyond the tip of 

 telson and is a little shorter than the exopod. — Length of the 

 largest spécimen, an adult female, 19.5mm; an adult maie 

 measures 18.2mm. 



Localities. — Stat. 1676, 2 spécimens; stat. 1736, 5 spéci- 

 mens; stat. 1760, 5 spécimens; stat. 1768, 1 spécimen; stat. 

 1800, 5 spécimens; stat. 1802, 4 spécimens; stat. 1849, 1 spéci- 

 men; stat. 1 856, 5 spécimens. 



130) 



