54 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.60. 



lamina is emarginate, and presents thus two teeth or angles, the cor- 

 responding margin in orthogonus being entire. A pronounced differ- 

 ence is in the caudal process at base of tibial division, this being very 

 much smaller in the present species and having ectad of it a low, 

 but broad laminate process (pi. 21, figs. 4 and 5). 



This species is a smaller form than the preceding, the male type 

 being 18 mm. long and 4 mm. wide. 



Locality. — Guatemala : San Rafael, one male and one female (O. F. 

 Cook, June 4, 1914). 



Type.—C^i. No. 852, U.S.N.M. 



SYNTHODESMUS, new genus. 



A genus closely related to Tunodesmus^ as above described, ex- 

 cepting in the structure of the gonopods, which differ conspicuousl3^ 

 In these the telopodite, which is bent forward at right angles to the 

 coxa, is proximally stout, but in the tibial region is abruptly slender. 

 It is straight and terminates in two short and slender processes, of 

 which the mesal one conducts the seminal canal. 



Genotype. — SynthodesTnus simulant ^ new species. 



129. SYNTHODESMUS SIMULANS, new species. 



Plate 21, figs. 6-9 ; plate 22, figs. 1, 2. 



Doisum brown excepting a pale median dorsal line of narrow 

 marks, which may be connected in the posterior region. Under the 

 lens small light dots, separated by a network of dark lines, show on 

 each side, particularly in an area at and above base of keel. Venter 

 and legs fulvous. The first two and the last two articles of antennae 

 commonly pale, the intervening ones fuscous. Anterior and lateral 

 margins of collum together forming an even arc, with the median 

 region somewhat flattened. Caudal margin only slightly arcuate, 

 being nearly straight (pi. 21, fig. 6) . General form of other keels as 

 in Tunodesmus orthogonus. Posterior angles of fourth keels nearly 

 rectangular. Posterior angles of fifth and succeeding keels acute 

 and produced more and more strongly in going caudad. Margins of 

 keels a little bent up, but not thickened. Pores caudad of middle, 

 opening well mesad of the margin (pi. 21, fig. 7). Sternites with 

 processes near bases of posterior pair of legs on segments of middle 

 and posterior regions of bod}^ those of posterior segments best de- 

 veloped, conical, shorter than in the species of Tunodesmus previ- 

 ously described (pi. 22, fig. 1). 



Anal scale pentagonal, the caudal end being obtusely angular, as 

 shown in plate 21, figure 8. 



An anterior leg of male is represented in plate 21, figure 9. 



