MARINE ISOPODA OF NEW ENGLAND, ETC. 351 



Bynldotea nodulosa Harger (Kroyer). 



Idothea nodulosa Kroyer, Naturhist. Tidssk., II, B. ii, p. 100, 1846 ; Voy. en Scand., 



Crust., pi. 26, fig. 2, 1849. 

 Reinhardt, Gr0nlands Krebsdyr, p. 34, 1857. 

 Lutken, Crust. Greeuland, p. 150, "1875." 



Synidotea nodulosa Harger, Am. Jour. Sci., Ill, vol. xv, p. 374, 1878; Proc. U. S 

 Nat. Mus., 1879, vol. ii, p. 160, 1879. 



PLATE VI, FIGS. 33-35. 



This species may be recognized most easily by the pleon, which is en- 

 tire, except for a slight incision near the base on each side, and tapers 

 to a blunt but not at all bind point. The articulated flagellum of the 

 antennae distinguishes it from Ericlisonia. 



The head and body are roughened and tubercular, having a prominent 

 median row of tubercles and coarse rugae along the sides of the thorax. 

 The head has a median notch in front, and immediately above this a 

 prominent tubercle directed forward, and succeeded on the median line 

 by two less prominent tubercles. In front of each eye is a still larger 

 tubercle, directed forward and projecting over the anterior margin of 

 the head ; behind and within, there are two smaller oval tubercles. The 

 eyes are large, convex, and very prominent. The peduncular segments 

 of the antenna3 (pi. VI, fig. 3-4 1) increase gradually in length from the first 

 and decrease in diameter from the second, which lacks the lateral in- 

 cision seen in Idotea. The flagellum is distinctly articulated, with about 

 nine segments, of which the last two are very minute. The maxillipeds 

 (pi. VI, fig. 35 a) have the external lamella (I) of an irregular shape, ernargi- 

 nate on the inner side and obtusely pointed. The outer maxillae (pi. VI, 

 fig. 35 b] are armed on their external lobe with strong, curved, pectinated 

 setae, which become much elongated and stout at the tip of the lobe. 

 The inner maxillae (pi. VI, fig. 35 c) resemble these organs in other mem- 

 bers of the family. 



The first four thoracic segments have their external margins rounded. 

 In the last three the margins are more nearly straight, but with rounded 

 angles. The first pair of legs (pi. VI, fig. 34 c) are much shorter than 

 the second, and the propodus in the first pair is bristly on what is, in the 

 ordinary position, the upper side. 



The pleon is short, and tapers from the base. It is convex, bears two 

 or three small tubercles on the median line near the base, and an im- 

 pressed transverse liue in continuation of the short lateral incisions. 

 The basal plate of the operculum (pi. VI, fig. 34 d) is oblique at the ba^ 

 with rounded angles, and is somewhat vaulted, with an oblique elevatfom 

 extending from the articulation to the inner distal angle. The inner 

 margin is straight, and the outer parallel with it to near the end. The 

 terminal plate is slightly oblique at the base, and is elongated triangular, 

 about twice as long as broad. The free margins are finely ciliated, except 

 at and near the base, and the inner margin of the basal plate bears also 

 scattered stouter hairs. The stylet of the males on the second pair of 

 pleopods (pi. VI, fig. 35 d, s) is longer and stouter than in any of our species 



