MARINE ISOPODA OF NEW ENGLAND, ETC. 351 



Synidotea noduloaa Harger (Kroyer). 



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

 Crast., pi. 26, fig. 2, 1849. 

 Eeinliardt, Gr0nlauds Krebsdyr, p. 34, 1857. 

 Liitken, Crust. Greenlaud, p. 1,50, " 1875." 

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

 Nat. Mus., 1879, vol. u, 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 bifid 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 stiU 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 i^eduncular segments 

 of the antennse (pi. VI, fig. 346) 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 maxillipeda 

 (pi. VI, fig. 35 a) have the external lamella (?) of an uTegular shape, emargi- 

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

 fig. 35 &) 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 fii"st four thoracic segments have theu* external margins roimded. 

 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 line in continuation of the short lateral incisions. 

 The basal plate of the operculum (pi. VI, fig. 34(7) is oblique at the base 

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

 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 shghtly 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 



