A NEW CHINESE ISOPOD, ICHTHYOXENUS GEEI. 



By Pearl L. Boone, 

 Aid, Division of Marine Invertebrates, United States National Museum. 



The species herein described was found parasitic on the " Tsi-fish " 

 or carp, probably Cyprinus cavpio taken from lakes and canals 

 around Soochow, China, by Prof. N. Gist Gee, of Soochow Uni- 

 versity, whose energetic investigations are constantly increasing our 

 knowledge of this hitherto neglected region. 



This is the fourth representative of the genus Ichthyoxenus^ a 

 group whose mode of life is peculiarly interesting. When young, 

 the isopod bores a hole in the body of a fish, just behind the lateral 

 fin, where it lives with its mate, developing so in size that it is im- 

 possible for it to escape through the opening by which it entered. 



The type species of the genus, I chthyoxenus jellinghausii Herk- 

 lots,^ described in 1870, was found parasitic on the fish Barbodes 

 maculatus Bleeker from Java, and in 1908 another host for this 

 species was reported by Maj. P. A. Ouwens,^ namely, the fish 

 Nemacheilus fasciatus van Hasselt from the Tji-Seroema near 

 Batavia. 



Ichthyoxenus montamts Schioedte and Meinert,* the second repre- 

 sentative of the genus, was described in 1884 as parasitic on Pwntius 

 sopJwres in the Himalayan Mountains. 



In 1913 Richardson described the third species of the genus, 

 Ichthyoxenus japonensiSj* from the following hosts : Acheilognathus 

 rhomheum (Schlegel), Gnathopogon elongata (Schlegel), ^c^«^?P'n«- 

 thiis tabira Jordan and Thompson, A. lanceolatum (Schlegel), A. 

 Gycnostigma (Jordan and Fowler), and A. liwybatunh Jordan and 

 Snyder, from Lake Biwa, Japan. 



Family CYMOTHOIDAE. 

 Genus ICHTHYOXENUS Herklots, 1870. 



ICHTHYOXENUS GEEI, new speciea. 



Plates 40 and 41. 



Female. — Body subovate, strongly convex, about 23.1 mm. long, 

 greatest width about 11.7 mm. Surface smooth; color (preserved 



I Archives Neerlandaises des Sciences, vol. 5, 1870, pp. 128-137, pi. 5, figs. 10-18. 

 'Natuurk. Tijdschr. Nederl.-Indie, vol. 67, 1908, pp. 29-35. 



'Naturk, Tidsskrift, Kjobenhavn, ser. 3, vol. 14, 1884, pp. 303-309, pi. 11, figs. 10-17. 

 *Proc. U. S. Nat. Mus., vol. 45, No. 1995, pp. 559-562, text-flgs. 1-6, 



Proceedings U. S. National Museum, Vol. 57— No. 2319. 



144382— 20~Proc.N.M.vol.57 32 497 



