ISOPODS OF NORTH AMERICA. 



337 



the posterior portion, two on either side of the median line, and three 

 lateral spines; the third thoracic segment has two spines on the 

 anterior portion, one on either side of the median line, four spines 

 on the posterior portion, two on either side of the median line, and 

 four lateral spines; the fourth segment has two spines on the anterior 

 part, one on either side of the median line, four spines on the poste- 

 rior part, two on either side of 



the median line, and four lateral / 



spines; the fifth segment has two 

 spines widely separated, one on 

 either side of the median line, 

 and one lateral spine; the sixth 

 and seventh segments have six 

 spines, three on either side of the 

 median line, and one lateral 

 spine. 



The first two abdominal seg- 

 ments have each eight small 

 spines, four on either side of the 

 median line. The terminal seg- 

 ment has one median row of 

 spines and a row on either side 

 of this and a lateral row. The 

 median row consists of five small 

 spines and one large terminal 

 spine. The dorsal row on either 

 side of the median row each con- 

 sists of four spines. The outer 

 marginal lateral rows each con- 

 sists of three spines, a pair at 

 the base, a pair about the middle, and a pair at the extremity. At the 

 base of the segment is a transverse row of four small spines. The 

 opercular valves have each a longitudinal row of eight spines. 



Both the anterior and the posterior pairs of legs are covered with 

 spines, the anterior ones more densely. 



Two specimens, one imperfect, were obtained by the U. S. Bureau 

 of Fisheries steamer Albatross at Fernandina, Florida. 



Tyj>e.C8.t. No. 11522, U.S.N.M. 



ARCTURUS BAFFINI (Sabine). 



Idotea baffini SABINE, Suppl. to App. to Capt. Parry's Voyage, 1824, p. 228, pi. i, 



figs. 4-6. 



Arcturus tuberculatus LATREILLE in Cuvier, Rgne Animal, 2d ed., IV, 1829, p. 139. 

 Ardurus baffini WESTWOOD, Trans. Entom. Soc., London, I, 1836, p. 72. MILNE 



EDWARDS, Hist. Nat. Crust., Ill, 1840, p. 123, pi. xxxi, fig. 1. G. 0. SARS, 

 28589-4)5 22 



FIG. 366. ARCTCRUS FLORIDANTJS. 



