188().] DURING THE VOYAGE OF H. M.S. 'challenger.' Ill 



8. Arcturus glacialis, u. sp. 



This new species comes near to the last, but may readily be 

 distinguished by the fact that the spines are more numerous, 

 shorter, and more slender. The single example, a female, measures 

 32 miUim. The dorsal surface is densely covered with short slender 

 spines, which extend on to the thoracic appendages and uropoda ; 

 the spines are of uniform length. The anterior margin of the head 

 is excavated by a shallow semicircular notch ; Ijetween and in front 

 of the eyes are a pair of long spines, inclined somewhat away from 

 each other ; the spines on the thoracic segments are disposed in the 

 following way : — each of the first four segments has a posterior and 

 anterior ridge as in other species ; both these are covered with 

 spines, as are also the epimera; between the two ridges in all but 

 the first segment are a pair of short spines ; each of the three 

 posterior thoracic segments is ridged, the ridge being beset with 

 spines except in the median dorsal line. The abdominal shield is 

 beset with spines, except in the dorsal median line, where it is 

 grooved longitudinally. 



Station 153; 16/5 fathoms. 



9. Arcturus abyssicola, n. sp. 



This species was obtained from two stations in the Pacific Ocean, 

 but near to each other. 



The length is about 20 millim., the length of the antennae 42 

 millim. Of the first four thoracic segments the second and third 

 are equal in size and rather longer than the first and fourth ; -each 

 of these segments is ridged posteriorly as in other species ; laterally 

 the tergum is produced into a short tubercle and there is a similar 

 tubercle upon the epimera ; on the first segment this tubercle is 

 prolonged into a spine ; on the inferior surface of the fifth segment 

 is a short median transverse ridge ; the first abdominal segment has 

 a pair of ventral tubercles ; the abdominal shield is keeled and 

 terminates in a blunt spine, it is covered with a few low scattered 

 tubercles. The anterior thoracic appendages are furnished with one 

 or two spines upon the proximal joints ; as in A. anna the posterior 

 thoracic appendages have not these spines. 



Station 184 ; 1400 fathoms. Station 281 ; 2385 fathoms. 



10. Arcturus studeri, n. sp. 



The extreme length of this species is 28 millim., length of antennae 

 30 miUim. The head has two pairs of long spines situated one 

 behind the other, behind these again is a ridge bearing a few short 

 spines ; the antero-lateral region of the head is notched ventrally 

 as in A. purpureus, &c. The four anterior thoracic segments are 

 subequal ; on the posterior ridge of the first segment are a pair of 

 minute tubercles on either side of the median dorsal line ; laterallv 

 are two long spines equidistant from each other and the dorsal 

 tubercles ; the lateral margin of the tergum is prolonged into two 

 outwardly directed spinous processes; in front of the posterior ridge 

 are four minute tubercles arranged transversely ; the second segment 



