| OCR Text |
Show 1886.] DURING THE VOYAGE OF H.M.S. 'CHALLENGER.' Ill 8. ARCTURUS GLACIALIS, n. 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 millim. 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 ; between 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 antennas 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 millim. 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 ventrallv 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; laterally 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 |
