no. 1831. NEW TROPICAL MILLIPEDS—COOK. 465 



Head small and depressed, facing nearly ventral, concealed far 

 under the projecting margin of the first segment. Vertex rather 

 obscurely and irregularly granular, with a rather distinct rounded 

 prominence at each of the posterior corners, behind the antennae; 

 surface pilose like that of the segments. Clypeus rather long and 

 narrow, distinctly emarginate on the sides, with a rather broadly 

 sloping transverse ridge; surface nearly smooth, scarcely pilose, 

 labrum narrow, smooth, with a shallow emargination and three 

 rather sharp teeth. 



Antennas rather slender, moderately pilose; second joint over 

 twice as long as the first and somewhat exceeding the third; other 

 joints lost. 



First segment distinctly narrower than the second, over half as 

 long as broad, widest in front of the middle. Dorsal surface strongly 

 convex hi the posterior part, concave in front, the anterior margin 

 distinctly upturned; irregularly granular, more even on the marginal 

 areas; densely and very minutely pilose. 



Second and following segments with three lateral lobes or areas 

 and three or four posterior, the latter separated by larger notches. 

 Surfaces of lobes rather evenly convex, the remainder of the surface 

 roughened with low irregular granules. 



Posterior segments somewhat gradually narrowed from about the 

 sixteenth. Carinte rather more strongly upturned than on the middle 

 segments and with the poriferous posterior lobe produced into a 

 long oblique spine bearing the pore near the base. Posterior margin 

 more distinctly scalloped in the middle than on anterior and middle 

 segments. Segments 18 and 19 have the two middle tubercles of the 

 posterior margin specially enlarged. 



Last segment distinctly projecting beyond segment 19 in the mid- 

 dle, though evidently exceeded by the long poriferous tubercles of 

 segment 19, incomplete in this specimen, as the figure indicates. 

 Surface less uneven than on preceding segments, but still distinctly 

 granular and pilose. Two minute setiferous tubercles along the 

 lateral margins on each side below the apex. 



RELATIONSHIPS OF THE FAMILY CRYPTODESMIDJ3. 



The difficulty of assigning Chatelainea to a satisfactory place in 

 the classification is due, in large measure, to the confusion that has 

 been allowed to gather around Cryptodesmus, the genus to which 

 some writers might refer Chatelainea. This name belongs, in reality, 

 to a little-known South American milliped, but has been used for 

 many and very diverse species from all parts of the tropical world. 

 It is generally considered that the tropical forms referred to the genus 

 Cryptodesmus or to the family Cryptodesmidse constitute a distinct 

 group, but most writers have hesitated to recognize the true extent 

 80796°— Proc. N. M . vol.40— 1 1 30 



