1880.] DURING THE VOYAGE OF H.M.S. 'CHALLENGER.' 109 



female there are several shorter ones in addition. The first abdo- 

 minal segment has a single row of comparatively short backvvardly- 

 directed spines ; on the second and third segments these spines get 

 to be considerably longer, especially the lateral spine on either side, 

 which marks the commencement of the abdominal shield. The 

 abdominal shield in both sexes is covered with longish curved 

 spines ; just above and near to the termination of its lateral margins 

 are an extremely long pair of spines directed outwards and slightly 

 upwards. The proximal joints of the antennae and of the thoracic 

 appendages are furnished with spines. The uropoda are tuberculate 

 in the male and spiny in the female. 

 Station 147; 160(3 fathoms. 



5. Arcturus purpureus, u. sp. 



This species is represented by a single female, which is of a 

 purplish colour. It measures 18 millim., the length of the antennae 

 is 31 millim. 



On the head between the eyes are a pair of long forvvardly curved 

 spines ; the hinder portion of the head is occupied by a rounded 

 median convexity ; on the antero-lateral margin is a very short 

 forwardly directed spine, beneath which the margin is excavated by a 

 semicircular notch. Of the first four thoracic segments, the fourth 

 is rather the shortest ; each of the segments bears an outwardly 

 directed spine on each side of the body, corresponding in position to 

 those upon the head ; close to the lateral margin of each segment 

 and projecting over the epimeron is another long spine ; the first 

 segment differs from the succeeding in having no free epimera, and 

 the lateral margin has two spines instead of one, of which the 

 anterior is the longer ; the fourth segment has also a second spine 

 at its postero-lateral margin. Of the three posterior thoracic seg- 

 ments the first is the largest ; the epimera of all have a long out- 

 wardly directed spine ; the first of these segments has in addition a 

 tergal spine on either side exactly overlying the epimeral spine. The 

 first abdominal segment has a pair of long lateral spines and a pair 

 of short ventral spines ; the third segment has a pair of lateral 

 spines. The abdominal shield is oval, with a faintly marked central 

 keel, terminating posteriorly in a long spine ; its lateral margins are 

 flattened and unite posteriorly ; on either side are two flattened 

 spines situated at equidistant intervals. The antennae and anterior 

 thoracic limbs have a few spines upon the proximal joints ; the 

 uro|3oda are granulated, but bear no spines. 



Station 23 ; 450 fathoms. 



6. Arcturus spinifrons, n. sp. 



This species reaches to a length of 13 millim., tiie antennae 

 measuring 20 millim. The body is extremely tuberculate, but there 

 are no spines except a single pair upon the head ; the lateral margin 

 of the head, as in A. anna, is notched ventrally. The four anterior 

 thoracic segments are subequal, each has a posterior ridge which 



