562 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.45. 



tip of the uropods and being 1 mm. shorter than the extremity of 

 the terminal abdominal segment. 



All seven pairs of legs are prehensile. The last pair has the carpus 



and merus dilated in rounded expansions on the inferior side. The 



merus is short, being about one-third the length of the ischium. In 



the last four pairs of legs these articles show an increasing expansion. 



Some of the specimens obtained are larger than the one figured 



and described, but in most of these the abdomen is curled up at the 



extremity. I have therefore taken the smallest one as the type. 



The male differs from the female in size, being much smaller; in the 



more symmetrical body, longer antennae, narrower 



head, and smaller terminal segment of the abdomen. 



The type-specimens, male and female, were taken 

 from Acheilognathus cijonostigma (Jordan and Fowler), 

 found in Lake Biwa, and two males and two females 

 were taken from the same host at Omi, Lake Yogo. 

 Other specimens are as follows: A male and a female 

 Fig. 6.— ichthy- on Ackeilognathus lanceolatum (Schlegel) from Funa- 

 NENsis^ Lake 7^^^' Kiusiu, Japan, and a male and a female on the 

 Bi-wA, FROM same host from Omi, Lake Yogo; a male and a female 

 THus^'cTONi- °^ Acheilognathus tabira Jordan and Thompson, MSS., 

 STIGMA, sev- from Lake Biwa; one female on Gnathopogon elongata 

 ENTH LEO OF (gchlegel) from Lake Biwa; two males and two fe- 



FEMALE. Xl4i. ^ O ' ^ ' ^ 



males from two specimens of Acheilognathus rhombeum 

 (Schlegel) from Lake Biwa; two males and two females from Achei- 

 lognathus limbatum Jordan and Snyder from Lake Biwa. 



This species differs from I. jellinghausii in the larger eyes, the 

 larger and more circular form of the terminal segment of the abdo- 

 men, the shorter uropoda, the shorter and differently shaped merus 

 of the seventh pair of legs, and the larger head and wider abdomen, 

 compared with the thorax. 



Type.— C&t. No. 45617, U.S.N.M. 



LIST OF REFERENCES. 



Herklots, J. A. Deux nouveaux genres de Crustac^s vivant en parasites sur des 

 poissons-epichthys et ichthyoxenos. Archives N6erlandaises des Sciences 

 exactes et naturelles, vol. 5, 1870, pp. 120-137, pi. 5, La Haye. 



OuwENS, P. A. Nog lets over Ichthyoxenus jellinghausii (Herklots). Natuurkundig 

 Tijdschrift voor Nederlandsch-Indie, vol. 67, 1908, pp. 29-35, Weltevreden. 



ScHicEDTE, J. C, and Meinert, Fr. Symbolae ad monographiam cymothoarum 

 crustaceorum isopodum familise. IV. Cymothoidas. Trib. II. Cymothoinse. 

 Trib. III. Livonecinse. Naturhistorisk Tidsskrift (3), vol. 14, 1884, pp. 221-421, 

 pis. 6-18, Kj0benliavn. 



Weber, Max.^ Die Siisswasser-Crust. des Indischen Archipels, nebst bemerkungen 

 iiber die Siisswasser-Fauna im Allgemeinen. Zool. Ergebnisse, vol. 2, 1892, pp. 

 557-560, pi. 30, fig. 1, Leiden. 



WiLLiNK, H. D. TiEENK. De "Songkeat" een vischparasiet. Natuurkundig Tijd- 

 schrift voor Nederlandsch-Indie, vol. 64, 1905, pp. 156-161, Amsterdam. 



1 1 have not been able to obtain this paper. 



