375 



ramus exceeding the outer by about 'A of its lengtli. Telsou oblong oval in 

 form, slightly tapering in its outer part, apical incision very short. Body 

 whitish, banded transversely with a brillant crimson, the bands being, as a 

 rule, rather narrow, 2 or 3 in each segment, and partly extending down the 

 coxal plates and the basal joints of the posterior pairs of pereiopoda, Length 

 of adult female reaching 12 mm. 



Memarls. — This form was at first announced in the year 1780 by 

 Otto Fabricius as Oniscus serrahts, and subsequently redescribed by Kroyer 

 under another name, viz., Ampliitlio'6 serra. It is the species first detected, 

 and may therefore proper! 3^ be regarded as the type of the genus. From the 

 other 2 species, it is easily distinguishable by the somewhat different arma- 

 ture of the body, and more especially by the peculiar form of the last pair 

 of epimeral plates of metasome. The colour of the living animal is very 

 beautiful and characteristic, though to some extent variable. 



Occurrence. — The species is not seldom met with on the whole Fin- 

 mark coast in moderate depths, ranging from 10 to 50 fathoms, among algse 

 and Hydroida. I have also found it in some places on the west coast of 

 Norway, rather plentiful, on rocky bottom, and Boeck states its occurrence 

 as far south as Haugesund, where however it is very rare. 



Distribution. — Arctic Ocean, widely distributed: Greenland (Fabr.), 

 Iceland (Torell), Spitsbergen (Goes), the Barents Sea (Hoeck), the Murman 

 Coast (Jarzynsky), the Kara Sea (Hansen), Labrador (Packard), Atlantic coast 

 of North America (Sidn. Smith); coast of Bohuslan (Loven). 



2. Acanthonotosoma cristatum, (Owen), 

 (ri. 131, fig. 2). 



Acaiithonolvs cristattis, Owen, Append, to the 2nd Voyage of Ross, p. n 90, PI. B, fig. 8—12. 



Syu. : Araphithoo cristata, M. Sars. 

 ,, Vertumnus cristatus. Goes. 



Body rather compressed, with the back strongly curved and distinctly 

 carinated throughout, the carina of the 4 anterior segments rather conspi- 

 cuous, though not forming any projections, that of the siicceeding segments 

 elevated to very strong laminar processes, acute at the tip; 1st segment of 

 nrosome with a similar strong dorsal projection. Cephalon about as in the 

 preceding species. Fourth pair of coxal plates with the outer part falciform, 

 and having the anterior edge evenly curved; posterior projection rather pro- 

 duced, though blunted at the tip; the 3 succeeding pairs each produced to 

 a posteriorly curving acuminate point. Epimeral plates of metasome with 

 the lateral corners, acutely produced, those of last pair greatly projecting, 

 but quite simple, not bilobate. Eyes very small, rounded, pigment bright 



