— 26 — 



feebly developed joint, the setas along the upper margin are 

 moderately strong, at least as numerous as and somewhat 

 shorter than those on the lower margin ; in . T. parva the setae 

 on the lower margin are shorter, thin, only about half as long 

 as the rather thin terminal setae, while the setae on the upper 

 margin are thin, short and scarcely as many (about 6) as those 

 on the lower margin (about 7). — Length of adult spécimens of 

 both sexes between 9 and io mm ; a large maie measures io.2 mm . 



Localities. — Stat. 1749, 1 spécimen; stat. 1760, about 

 5o spécimens; stat. 1768, 8 spécimens; stat. 1849, about 

 100 spécimens; stat. 1 856, nearly 5o spécimens; stat. 1869, 

 1 spécimen. 



Remarks. — The material contains about 200 spécimens, 

 most of them of about the same size ; many of them are adult 

 maies, having the copulatory appendages of the anterior pleopods 

 well developed. The spécimens are slightly more than half as 

 long as T. gregaria, the average length of which is judged by 

 Sars to be i8 mm . For thèse reasons I consider the différences 

 between T. gregaria and the form described here as T. parva 

 to be of spécifie value. 



Genus NEMATOSCELIS, G. O. Sars 



Four species have been established by Sars in the Chal- 

 lenger Report ; severalyears after Chun erected two additionai 

 species. But the study of the collection in hand revealed that 

 our knowledge of the genus is very imperfect. Of the large 

 species N. megalops, G. O. Sars, the maie has not been described, 

 and it differs strongly from the female in the shape of rostrum. 

 Two of the forms established by Sars, viz. N. tenella and 

 N. rostrata, dififer from his two other species in possessing 

 a latéral denticle on the lower margin of the carapace near its 

 posterior end, but the fine Monaco material shows that such 

 denticles have not essentially a spécifie, but quite another signi- 

 ficance in this genus. 



