1896.] >-ATUEAL SCIENCES OF PHILADELPHIA. 259 



Tylodesmus crassipes. 



Color entirely black, legs and antenna yellowish ; copulatory legs 

 "without the spine present in Prepodesmui; and with the interior 

 lamina broad and flabellate ; anterior male legs slightly, though 

 distinctly, crassate; length of male 40 mm., width 4.5 mm. ; length 

 of female 43 mm. ; width 5.6 mm. 



Tylodesmus amoebus. 



Anterior half of first segment, the carinje of the second and third, 

 and the whole of the poriferous segments, except the last two or 

 three, bright red ; the remainder of the body is black ; legs and 

 antenna pale; legs of both sexes distinctly more slender than in the 

 preceding species ; sexes not strikingly unequal, though the male 

 is more slender and has somewhat longer legs ; length 35 mm., width 

 of male, 4 mm., of female, 4.5 mm. ; locality, Muhlenburg Mission. 

 The color of this species is almost exactly that of Frepodesmus 

 mimus. 



Lyrodesmus nigerrimxis. 



The genus is evidently related to the last, and has a closelv similar 

 copulatory foot ; it is distinct in being more slender and depressed, 

 and in having the first segment lenticular or fusiform in outline, 

 rather than hemispheric-elliptical as in the two preceding genera. 

 The species is deep, shining black, including the legs and antennae ; 

 length of male 35 mm., width 4 mm., legs 6 mm., antenna 8 mm. in 

 length. Very rare, only two specimens found. A third, nearly 

 white in color and somewhat diflferent in form, may prove to be 

 specifically distinct. 



Cheirodesmus ater. 



First segment as in Lyrodennu-s, but the angles not so pointed ; 

 body more slender, narrower, dorsum flat ; carina with square 

 corners, so that the poriferous callus projects from a nearly straight 

 edge ; copulatory legs less complicated, the slender branch shorter; 

 color uniform black, legs and antenna yellowish ; length 30 mm. ; 

 •width 3.75 mm. 



Cheirodesmus discolor. 



Similar to the preceding in size and form, but distinct at least in 

 color ; an area around each pore, and a moderately broad median 

 line, yellow ; legs and antenna reddish-yellow ; rare, only one pair 

 taken, near Muhlenburg Mission. 



