336 BULLETIN 54, UNITED STATES NATIONAL MUSEUM. 



The first abdominal segment has one lateral spine on each side; the 

 second segment has two dorsal spines, one on either side of the median 

 line. The terminal segment has one lateral spine on each side near 

 the base. It is rounded in outline posteriorly, with two lateral spines 

 on either side, one a little below the middle and one near the posterior 

 margin of the segment. There is also a large terminal spine on the 

 dorsal surface. 



The opercular valves are armed each with a single spine about the 

 center of the valve. The penultimate joint of the second, third, and 

 fourth anterior pairs of legs is armed with a single spine. 



One specimen of this species was taken by the U. S. Bureau of Fish- 

 eries steamer Albatross near Aves Island, Caribbean Sea. 



Ti/pe.~C&t. No. 9113, U.S.N. M. This species closely resembles 

 Arcturns jnirpureus Beddard, differing from that species in having 

 two dorsal spines on the second abdominal segment, spines on the 

 opercular valves and at the base on the outer margin of the second 

 joint of the peduncle of the second pair of antennte, in wanting spines 

 on the proximal joints of the anterior thoracic appendages, with the 

 exception of the penultimate joint, and in the greater length of the 

 first pair of antenna?. 



ARCTURUS FLORIDANUS Richardson. 



Arcturns foridanus Richardson, American Naturalist, XXXIV, 1900, p. 230; 

 Proc.'u. S. Nat. Mus., XXIII, 1901, pp. 548-549. 



Locality. — Fernandina, Florida. 



Depth.— ^1Z fathoms; 270 fathoms. 



Head with deep anterior excavation, on each side of which the lateral 

 margins are produced, bearing each a single spine at the outer angle. 

 On the anterior portion of the head are two long spines situated 

 between the eyes. Two long spines are placed on the posterior por- 

 tion of the head, between the line of the eyes, on either side of which 

 are two small spines, one near each qjq and one on the lateral margin. 

 The first pair of antennse are short, reaching only half the length of 

 the third joint of the second pair of antenna?. The first joint of the 

 second pair of antenna? is short and unarmed; the second joint has one 

 short spine at the liase and three long ones at the upper end; the third 

 joint is nearly three times as long as the second joint, and has two long 

 spines at the upper end; the fourth joint is armed wdth a single spine; 

 the fifth joint is unarmed; the flagellum is nine-jointed. 



The first thoracic segment has two dorsal spines on the anterior 

 part, one on either side of the median line, six spines on the posterior 

 part, three on either side of the median line, and two lateral spines; 

 the second thoracic segment has three spines on the anterior portion, 

 one in the median line and one on either side of it, four spines on 



