CRUSTACEA MALACOSTRACA III. 41 



dorsal median line either a pair of spines or three or four spines, either in a group (fig. 7 a) or in a 

 transverse line (fig. 7 b); these spines are sometimes short or moderately short, sometimes long or 

 very long. Besides, the three or four anterior segments have the lateral margins at the insertion of 

 the coxae furnished with spines, from one to three or four at each margin (fig. 7 a). Frequently some 

 of the spines or most of them, especially those at the middle of the segments, are seemingly wanting, 

 but they may have been broken off. In a male from the "Ingolf" Stat. 89 each segment has only one, 

 but very long, dorsal spine, and a similar spine is found 011 the head. The coxse have also spines, 

 from one to four or five (figs. 7 a, 7 b and 7e); sometimes one of these coxal spines or one of the 

 supercoxal spines is very long. — First pair of legs normal, and similar in both sexes. 



Abdomen (figs. 7 b and 7 d) oblong-ovate, about or somewhat less than half as long again as 

 broad, with or without a single spine at each lateral margin, but somewhat more upwards a single 

 pair, and besides two or three or, rarely, four pairs of dorsal spines; these spines vary much as to length 

 and thickness, but the posterior dorsal pair are generally thick. The posterior margin of the abdomen 

 is rounded; the uropods about as in M. Boeckii. — The median lamella of the male operculum (figs. 

 7g — 7I1) without ventral spines, two and a half times as long as broad, broadest near the base and 

 tapering to somewhat beyond the middle, while its distal part has the margins nearly parallel and the 

 end in the main truncate; the hind margin of each pleopod is slightly sinuate, and at the outer margin 

 with a minute tooth directed backwards. 



Length of a female 3-1 mm., of a male 2"8 mm. 



Remarks. It is evident from the description that this species is very variable as to length 

 and curvature of the eye-stalks, and in number and length of the spines on the body. (The specimens 

 figured have the spines moderately strongly developed.) The specimens vary from station to station, 

 and, besides, sometimes considerably from the same station. But it must be emphasized that the vari- 

 ation seems to be independent of the bottom temperature, and that it is quite impossible to separate 

 the specimens from the cold area as another species. The antennula: are uncommonly uniform in 

 adult specimens, but younger specimens have only 2 long joints instead of 3 in the flagellum, and 

 second peduncular joint is shorter than in the adults. 



Especially by the curious shape of the blind eye-stalks M. acanthifera is instantly separated 

 from all other arctic or European species, but it agrees in this feature with M. truncates Richardson 

 (1908) from the North-West Atlantic. According to the description and figures published by the 

 American authoress, M. truncata cannot be identical with M. acanthifera, as it differs in three features, 

 viz.: the surface of M. truncata is smooth, the end of abdomen uncommonly broad and truncate, and 

 a higher number of joints is found in the antennulse. The antennulee of M. truncata contain according 

 to description and figure 8 joints, but the minute terminal joint has certainly been overlooked, as the 

 eighth joint on the figure is as long as the seventh; the result is that the antennulse contain 9 joints. 

 Furthermore the authoress referred only 2 joints to the peduncle, but this always comprises three 

 joints; consequently the flagellum contains 6 joints, the first and the terminal short, while the remaining 

 four joints are longer. But I never found more than 3 longer joints in the flagellum of M. acanthi/era. 



In the marsupium of a female from Stat. 105 was found a new species of the genus Spkaronella, 

 belonging to the parasitic Copepoda. 



The Ingolf-Expedition. III. J. ° 



