224 bulletin: museum of comparative zoology. 



Chelodesmidae. 



Amphelictogon, gen. nov. 



Differing from Leptodesmus Saussure (type L. earncns) primarily 

 in the character of the male gonopods which bear at the end of the 

 principal (caudal or ventral) branch a long and slender seminiferous 

 style which is more or less coiled; the upper or anterior branch ends 

 in a narrower flattened blade which is also somewhat coiled, curving 

 proximad and ordinarily crossing the one of the opposite side. All 

 have one or two teeth on the caudal margin of the keels. With few 

 exceptions the legs and antennae are reddish in whole or in part. 



Genotype. — A. cuhanus, sp. nov. 



174. Amphelictogon cubanus, sp. nov. 



Tijpe.— M. C. Z. 4,484. Parafypes.— M. C. Z. 4,485. Cuba: 

 Guantanamo, Bayate de Guantanamo, 1913. C. T. Ramsden. 



Differentiated from A. couloni in having the style coiled in the 

 reverse direction at the base, its course running mesad and then 

 ventrad, ectad and around, the free distal portion running in tangent 

 to the lower inner side of the coil instead of to the upper. The shoulder 

 on the distal side of dorsal branch much smaller than in A. couloni. 



Second, third, and fourth articles of antennae not much differing 

 in length, long and slender; sixth article thickest; seventh hemi- 

 spherically rounded. 



Anterior and lateral margins of keels evenly and continuously 

 rounded, smooth, thickened progressively more and more in going 

 to the caudal angle. Caudal angles broad, only little produced as 

 usual in species of Leptodesmus. The caudal margin of each keel 

 presents two nodular thickenings projecting as weak rounded teeth 

 of which the more ectal is the larger. Dorsal surface of metazonites 

 divided into three transverse rows of polygonal areas of which those 

 of the anterior row are largest and in going caudad become more 

 vaguely separated. Dorsum only slightly convex, the keels hori- 

 zontal. Anal tergite subtriangular, sides concave, tip truncate. 



Sternites without processes or that of the fourth somite with a 

 longitudinal furrow forming a slight ridge on each side which con- 

 tinues forward as a slight low cone. 



When in full color the dorsum is dark chocolate-brown to black with 



