28 



PROCEEDINGS OF THE NATIONAL MUSEUM. 



VOL. 42. 



The first three and the last three segments of the thorax are sub- 

 equal in length, each being about IJ mm. long; the fourth segment 

 is a little longer than any of the others, being 2 mm. in length. Epi- 

 mera are present on all the segments except the first; on the second 

 and third segments they are narrow and bilobed and extend only half 

 the length of the lateral margin. They are narrow also on the fourth 

 segment and extend tliree-fourths the length of the lateral margin. 

 On the last three segments they are wide plates, with the outer post- 

 lateral extremity acutely produced beyond the posterior margin of 

 each segment. 



The abdomen is composed of four segments, or three short segments 

 anterior to the long terminal segment. There is a suture on either 

 side of the terminal segment indicating another 

 partly coalesced segment. The terminal segment is 

 6 mm. long and 3^ mm. wide; it is rounded posteri- 

 orly. On its dorsal side the posterior third portion 

 of the segment is obliquely flattened, and has a large 

 median boss, surmounted by a tubercle. 



The first three pairs of legs are prehensile, the 

 first pair having a larger and more inflated propo- 

 dus; they are directed anteriorly. The fourth pair 

 of legs is much shorter than any of the others and 

 folds back laterally. The following three pairs are 

 ambulatory, increasing slightly in length and di- 

 rected posteriorly. 



Only one specimen, a female, was collected in Japan. 

 The type is in the United States National Museum, 

 Cat. No. 43133. 



In addition to the new species, two other spe- 

 cies of Cleantis have been described from Japan, C. 

 isopus IVIiers ^ and C. strasseni Thielemann.^ The 

 present species is, however, closer to C. ocddentalis 

 Richardson from Magdalena Bay, Lower California. It differs from 

 C. occidentalis in lacking the groove on the posterior portion of the 

 anterior part of the terminal abdominal segment, which is elevated 

 above the posterior fourth part of the segment, and in the presence 

 of a boss surmounted with a tubercle in the center of the depressed 

 area at the posterior extremity of the terminal segment. 



The narrow, elongate form of the body, with sides almost parallel 

 and the disposition of the legs would seem to place this species among 

 the tube-dwelling forms. Cleantis tuhicola Thomson was found 

 in a tube formed of a "hollow stem of some marine or littoral plant." 



> Journ. Linn. Soc. London, Zool., vol. 16, 1883, pp. 80-81, pi. 3, flgs. 9-11. 



» Abhandlungen der math.-phys. Klasse der k. Bayer. Akademie der Wissenschaften, U. Suppl., vol. 3. 

 1910, pp. 07-C9. 



Fig. 1. Cleantis 

 J A p o N :c A . X 3. 

 (Deaytn by Miss V. 

 Dandridge.) 



