418 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



guelen Island by Willemoes-Suhm,* who describes the sacs attached to 

 the fifth thoracic segment and attaining, as the young develop, a diame- 

 ter of three to four millimeters. 



Taiiais vittatus Lilljeborg (Rathke). 



Crossurus vittatus Ratlike, Fauna Norwegens, p. 39, pi. 1, figs. 1-7, 1843. 

 Tanais tomcntosns Kroyer, Naturhist. Tidssk., B. iv, p. Ib3, 1842; ibid., II, B. ii, 

 p. 41-2, 1847; Voy. en Scand., Crust., pi. xxvii, figs. 2 a-q, "1849." 



Lilljeborg, Ofvers. Vet.-Akad. Forh., Arg., viii, p. 23, 1851. 



Meinert, Crust. Isop. Amph. Dec. Danise. p. 86, "1877." 

 Tanais hirticaudatus Bate, Rep. Brit. Assoc., 1860, p. 224, 1861. 

 Tanais vittatus Lilljeborg, Bidrag Kiiim. Crust. Tanaid.,p. 29, 1865. 



Bate arid West wood, Brit. Sess. Crust., vol. ii, p. 125, 1866. 



Stebbing, Traus. Devon. Assoc., 1874, p. (7), and 1879, p. (6); Ann. Mag. 

 Nat. Hist., IV, vol. xvii, p. 78, 1876. 



Verrill, Am. Jour. Sci., Ill, vol. x, p. 38, 1875. 



Macdonald, Trans. Linn. Soc., II, Zool., vol. i, p. 67-70, pi. xv, 1875. 



Harger, Proc. U. S. Nat. Mus., 1879, vol. ii, p. 162, 1879. 



PLATE XIII, FIGS. 81, 82. 



This species is at once recognized among our Isopods by the pleon, 

 which is beset with bristly hairs at the sides, and crossed by two rows of 

 similar hairs near the posterior margins of its first two segments. 



The body, though small, is rather robust, the length being about five 

 times the breadth, which is greatest at the first free, in reality the second, 

 thoracic segment. The head and united first thoracic segment is short, 

 not longer than broad. The eyes are distinctly articulated and much less 

 in diameter than the bases of the anteunulaj. The antennulse are shorter 

 than the head and first thoracic segment, and are composed of three seg- 

 ments, of which the first is longer than the other two together, while 

 the second and third are of about equal length; the third segment is 

 terminated by one or two rudimentary segments, surmounted by a tuft of 

 straight bristly set*. Similar setae arise from the terminal portions of the 

 two preceding segments. The antennae are as long as the autennuhe, but 

 more slender, and consist of a five-jointed peduncle, somewhat setose like 

 the auteuuulae, and terminated by a rudimentary flagelluin beset with 

 setae. The basal plates of the niaxillipeds are ciliated externally, and 

 meet. each other on the median line so as to form a keel narrowing back- 

 wards ; distally they become thicker and bear a four-jointed palpus, of 

 which the second and third segments are dilated internally and ciliated, 

 and the fourth is spatulate and ciliated at its extremity. The inner 

 ruaxillre have one of the lobes of the usual form and position, and armed 

 with short, curved spines at the tip, while the other is bent backward 

 and bears several elongated cilia at the tip, and by its constant motion 

 urges a stream of water through the branchial cavity. 



The first pair of legs are much enlarged and extend, in their natural 

 position, beyond the head, and the "hand" is ordinarily directed nearly 

 downward. The digital process of the propodus bears a broad lobe on 

 its inner side, and an acute tooth at its extremity ; at the side of the lobe 



*Zeit. Naturges., B. xxiv, p. xvii, 1874. 



