12 PEOCEEDIISrGS OF THE NATIONAL MUSEUM vol. 72 



SiphonacTne in having joints 1 to 4 much narrower and more slen- 

 der, while joint 5 is abruptly larger and more nearly equal to 

 joint 6. Also the body is much more slender and the nimiber of 

 segments is much greater, approaching twice as many, and perhaps 

 exceeding any other milliped. A diplopod with 192 segments, as 

 counted on one of these specimens, has a total equipment of 750 

 legs, and may be the nearest approach to a literal " thousand legs." 



ILLACME PLENIPES, new species 



Body very slender and flexible, filiform, strongly and evenly convex, 

 moderately pubescent on all of the exposed surfaces ; number of seg- 

 ments attaining 192, with a length of 36 mm. and a width of 0.7 mm. 

 in the largest female specimen ; other individuals 26 to 29 mm. long, 

 0.5 to 0.6 mm. wide, with 136 to 152 segments. 



Head rather narrowly triangular-cordate, the vertex more densely 

 hirsute, the hairs rather short, the clypeus with longer and sparser 

 hairs, nearly naked above the rather blunt-pointed labium; position 

 of head nearly vertical, not strongly recurved under the body. 



Antennae inserted at the sides of the head, moderately hirsute, 

 abruptly capitate-clavate, subgeniculate, the terminal joints carried 

 at the sides of the head, the second and third joints at the lateral 

 margin of the first segment; joints 2 to 4 gradually thicker but much 

 smaller and narrower than joints 5 and 6 ; joint 2 somewhat longer 

 than joints 3 and 4, which are subequal and nearly as broad as long; 

 joint 5 also about as broad as long, but much thicker than joint 4; 

 joint 6 slightly narrower than joint 5, and distinctly longer, about 

 one and one-half times as long as broad, cylindric-oval, slightly 

 narrowed toward the end; joint 7 projecting as a rather broad 

 frustum about one-sixth of the length of joint 6 ; olfactory cones not 

 prominent. 



First segment with the lateral margins evenly rounded and the 

 anterior margin nearly parallel with the posterior; the surface more 

 even than on other segments, which are abruptly convex behind the 

 transverse constriction. 



Penultimate segment without legs, the large pleura meeting in the 

 middle and apparently united, but the sutures indicated by a fine 

 median groove; last segment converging to a broadly rounded apex, 

 not projecting beyond the margins of the valves, scarcely equal to 

 the margin when viewed from the side. 



Type.—C^it No. 976, U.S.N.M. 



Numerous specimens were collected by O. F. Cook in San Benito 

 County, Calif., November 27, 1926, a short distance after crossing the 

 divide between Salinas and San Juan Bautista. Only one colony 

 was found, in a small valley of a northern slope wooded with oaks, 

 under a rather large stone. The living animals were nearly white, 

 moved very slowly, and rolled themselves into regular, close spiral 

 coils when disturbed, the coils with three or four turns. 



