ISOPODS OF NORTH AMERICA. 527 



"The six abdominal segments are distinct,- regularly diminishing 

 in size posteriorly, and the first five show rudiments of pleopods in 

 the form of slight rounded eminences on the ventral surface. In 

 Palsegyge barrel, Giard and Bonnier describe the male as having rudi- 

 ments of pleopods on the first three abdominal segments only (p. 70), 

 but in a later paper the same authors speak of the abdominal segments 

 of the male in the genus Palsegyge as being all furnished with these 

 rudiments. (Bull. Sclent., XXII, 1890", p. 373.) The last segment of 

 the abdomen is very small, cordate in form, being very narrow ante- 

 riorly, and having its hinder margin notched; its greatest breadth is 

 about equal to the length." CALMAN." 



A description of the first larval stage of this form follows; as it is 

 characteristic of this stage in other Epicaridea it is not necessary to 

 quote the description. 



PSEUDIONE GALACANTH/E Hansen. 



Pseudione galacanthtc HANSEN, Bull. Mus. Comp. Zool. Harvard College, XXXI, 

 1897, pp. 118-120, pi. v, tig. 22 L RICHARDSON, Proc. U. S. Nat. Mus., XXI, 

 1899, p. 869; Ann. Mag. Nat. Hist. (7), IV, 1899, p. 338. BONNIER, Trav. de 

 la Station Zool. de Winiereux, VIII, 1900, pp. 304-306. RICHARDSON, Proc. 

 U. S. Nat. Mus., XXVII, 1904, p. 78. 



Localities. Gulf of California, in* the branchial cavity of Galacan- 

 tha diomedise var. parvispina, Faxon; near Flattery Rocks, Washing- 

 ton, on Munnida quadrispina- Benedict. 



Body of female somewhat asymmetrical. Length 11 mm. Width 

 8 mm. 



Head as wide as long, 3 mm. : 3 mm. , with the anterior margin 

 straight. The posterior margin is rounded. Eyes absent. The first 

 pair of antennas are composed of three articles. The second pair are 

 composed of five articles. 



All the seven thoracic; segments are distinct. The lateral parts of 

 the first four segments are divided into a large anterior lobe and a 

 small posterior lobe. Ovarian bosses are present on the first four seg- 

 ments, situated on the anterior portion of the lateral parts of these 

 segments. The epimera are not distinctly separated on any of the 

 segments, but occupy the small posterior lobe of the lateral margin of 

 the first four segments and the entire lateral margin of the last three 

 segments. All six segments of the abdomen are present. The first 

 five have the lateral parts well developed and produced in elongated 

 lamella, which almost entirely conceal the underlying pleopoda. The 

 sixth or terminal segment is small, and has the lateral parts undevel- 

 oped. The uropoda are simple, single- branched, elongated lamella?, 

 attached to the sixth abdominal segment. The pleopoda are five 

 pairs of double-branched elongated lamella? attached to the first five 



Ann. N. Y. Acad. Sci., XI, 1898, pp. 274-281. 



