682 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.xxi. 



beyond the hairy base ; the compressed portion is strongly decurved and bears in 

 the simis a usually large and nodifoi-m process; beyond this is a usually long and 

 slender, flexuons liagellum: Subfamily Gomphodesmin.e, p. 687. 



S\abfamily INCARFTODESlMIlSr^. 



The genera of this siibdivisiou are two in number and agree closely 

 in habit and small size. Tliey are most conspicuously difterent from 

 the remainder of the family in having the copulatory legs short and 

 comparatively straight, not bent iu the middle and produced into the 

 long, flexuons flagellura which distinguishes other Gomphodesmida? 

 among Merocheta. 



ANALYTICAL KEY TO THE GENERA OF MARPTODESMIN.E. 



Repngnatorial pores 11, segments 11 and 14 poreless; copulatory legs abruptly 

 narrowed immediately above the broad base; distally with two subequal simple 

 divisions: Genus Mar2)todesm us, Tp. 682. 



Repngnatorial pores 13, segments 11 and 14 provided with pores; copulatory legs 

 subconic, narrowed toward the apex and provided with a long, mesially directed, 

 curved process nud two somewhat uneijual terminal divisions, the ventral (posterior) 

 stouter and bifid at the apex ; the other more slender, with several mesially directed 

 teeth: Genus Harmodesmus,T^. 685. 



Genus MARPTODESMUS Cook. 

 Marptodesmus Cook, Proc. U. S. Nat. Mus., 1895, XVIII, p. 92. 



Description. — Body of medium size, about four times as long as broad, 

 oblong, very abruptly narrowed anteriorly, subtruncate posteriorly. 



Labrnm with shallow emargiuation and three small, rounded teeth of 

 modei-ate length; supralabial bristles very numerous. 



Anteun* tiliform, second joint longest; joints 2,3,4,5,6 subequal; 

 olfactory cones four, arranged in a square. 



First segment three times as broad as long; anterior and i^osterior 

 margins medianly straight and subparallel; lateral end rounded, the 

 posterior corner broadly truncate, the anterior slightly so; the segment 

 is much broader than the head, twice as long, and somewhat narrower 

 than the exposed portion of the second segment. 



Segments smooth and shining, without markings. 



Lateral cariu;^ approximate, about one-fourth as wide as the body 

 cavity, inserted halfway up; a tine raised margin broadest laterad, 

 especially on poriferous and caudal segments. 



Repugnatorial pores opening subdorsally iu a large, deep, rounded 

 depression of the outer slope of an intramarginal ridge of segments 5, 

 7, 9, 10, 12, 13, 15, 1(3, 17, 18, 19. 



Preanal segment very short; anal segment very short, the apical por- 

 tion triangular, truncate at apex, and with four punctations there; 

 twelve other punctations, ten located as in Plate LV, fig. 2j, and 

 two others lower down on the sides, below the level of the carime (Plate 

 LV, fig. 2h\. 



