68 BULLETIN 46, UNITED STATES NATIONAL MUSEUM. 



Genus II. — Oh^etaspis, gen. nov. 



Body slender, riot muck depressed, more convex that in Polydesmus, 

 but not so much as in Scytonotus. 



Antennae with the third and sixth joints equal, the latter strongly 

 swollen, second and fifth subequal, fourth equal to seventh and eighth. 

 Segments 20; lateral plates distinct, but not as in Polydesmus, slightly 

 angled, serrate; dorsal plates smooth, excepting a row of indistinct, 

 setigerous tubercles along the anterior and posterior margins, no me- 

 dian, dorsal line; last acuminate. Eepugnatorial pore rather large, 

 placed on a moderately large and round tubercle, near the outer bor- 

 der of the 5, 7, 9, 10, 12, 13, 15, 16, 17, 18, 19 dorsal plates. Pahs of 

 feet, $ 30, ? 31. 



This genus is related to Polydesmus and Scytonotus, but can be easily 

 separated by the character of the dorsal plates. 



2. Chsetaspis albus, sp. nov. 



White throughout. Slender, small, slightly acuminate before. An 

 tennae exceeding the width of body, snbclavate. First dorsal plate 

 large, semicircular, angles not produced, provided with five rows of 

 hairs. Other dorsal plates with the posterior angles a little produced, 

 lateral margins with 3-4 setigerous teeth; rows of hairs 2 to 3. Feet 

 rather long, S crassate, 2 slightly crassate. $ copulation foot erect, not 

 as in Polydesmus; composed of two pieces, the outer curving outwards 

 and then inwards so that the ends almost touch over the median line 

 of body, rather robust, somewhat flattened, the end apparently divided 

 into three pieces — a small lobe, followed by a long and slender one with 

 the end turned sharply downward, and this by a large flat bifid piece; 

 inner piece narrow and thin, sickle shaped, the end curving up be- 

 tween the branched lobe of the outer piece; coxae with a few long 

 hairs. Seventh dorsal plate enlarged. Length of body G-7.5 mm ; width, 

 0.3-0.5 lum . 



Habitat. — Bloomington, Ind. 



I have examined four 9 2 and three $ $ . It seems to be more under- 

 ground in its habits than the other species of this family known to me. 

 I have always found it under logs buried rather deep in the ground. 

 I thought at first this might be the young of some other Polydesmidce, 

 but having found several males and taken a pair in the act of copula- 

 tion, I have decided that it must belong to a new genus. 



Genus III. — Scytonotus Koch. 



3. Scytonotus cavernarum, sp. nov. 



Allied to nodulosus Koch. Pure white throughout. Slender, some- 

 what depressed, acuminate anteriorly. Antennae exceeding the width 

 of the body, clavate. First dorsal plate elliptical, angles sharp; scales 

 arranged in five, transverse series, anterior row sharp, setigerous, all 



