132 MESSES. NOEMAN AND STEBBING ON 'HKE 



1872. Paranthura norvegica, G. O. Sars, Bidrag til Kundskaben orn Dyrelivct paa vore Havbanken, 

 Vidensk. Selsk. Forhandi. 1872, p. 88. 



1875. Aiithura arctica, Heller, Crustaceeu, Pycnogouideu und Tunicaten der k.-k. Osterr. Ungar. 

 Nordpol Expedit. p. 14, pi. iv. figs. 9-12 ; 1876. G. O. Sars, Prodrom. descrip. Crust, et 

 Pycnogou. in exped. Norveg. 1876, in Arehiv for Mathemat. og Naturvidenskab, p. 347. 



Perseon having each of the five first segments nearly or quite twice as long as broad, 

 slightly carinated on each side above ; three first strongly keeled below, first of equal 

 breadth throughout, second greatly constricted behind, so that here is the narrowest 

 part of the whole body ; third, fourth, and fifth segments gradually but only slightly 

 widening, and with the last of these the body attains its greatest diameter; anterior 

 margin of third segment slightly four-lobed, the lateral lobes produced outwards as small 

 protuberances ; fourth, fifth, and sixth segments with a central longitudinal dorsal 

 impression anteriorly; last segment of perason short, about one third the length of the 

 penultimate. 



Pleon very short, the whole (exclusive of telson) scarcely equalling the length of the 

 penultimate segment of the perseon, but with the segments clearly distinguishable. 



Both pairs of antennae with the joints of their peduncles rounded, last joint of peduncle 

 of inferior pair twice as long as the third ; flagella of both pairs multiarticulate. 



First gnathopods (fig. i. gn^) strong ; the hand large, ovate or somewhat triangular, 

 united by the lower part of its base to the little wrist, and with the proximo-dorsal 

 portion produced backwards into a large rounded lobe, which is received into a socket 

 formed by the concave rounded lobe developed on the meros ; palm occupying the entire 

 lengtli of the lower margin of the hand, slightly concave, edged with spines, each of 

 which is found, when examined with a high power, to be itself margined with very 

 minute spinules and to be tipped with a cilium. 



Second gnathopods (fig. i. gnr) and first peroeopods of nearly similar form to the 

 first, but more slender, and the lobe at the base of the hand much less de\eloped. 



The hinder peraeopods are longer and more slender (fig. i. ^^^T*)' iio* subchelate ; 

 liand and finger long and slender, subequal to each other, and each two to three times 

 as long as the wrist ; front margin of hand edged with fine down, and furnished with 

 about six spines set at equal distances ; these spines are themselves spined on the 

 edge. 



Uropods (fig. I. PI. d) with the outer plate, which arches over the telson, short and 

 wide, much broader than long, and somewhat retuse, with a minutely dentated margin ; 

 inner plate much longer, subequal to the telson, sharply keeled on the underside; 

 the second joint ovate and much shorter than the first, the inner margin smooth or very 

 slightly crenulated. 



The telson is shortly spear-shaped, the apex rather blunt. 



Lengtli of a large specimen one inch and an eighth, this being the largest known 

 species of the family. 



