50 PROCEEDINGS OF THE ISTATIOlSrAL MUSEUM. vol. GO. 



Genotype. — Atylophor rafaelanus^ new species. 



This genus is related to Trichotnorpha^ a genus represented by nu- 

 merous species in Colombia and Ecuador. It differs from this genus 

 in having the anterior legs of the male without tarsal pads and other- 

 wise without special modification. The tarsus has a greater propor- 

 tionate length in all the legs. The keels are more weakly developed, 

 as are also in particular the processes of their posterior angles. It also 

 suggests the Guatemalan Eutyporachls, but differs in the form of the 

 gonopods and in the smaller proportionate length of the sixth article 

 of the legs. 



125. ATYLOrHOR RAFAELANUS, new species. 



Plate IS, figs. 8-11 ; plate 19, figs. 1-3. 



Brown, with keel borders fulvous, area narrow in correspondence 

 with reduction of keels. Dorsum arched. Keels high, narrow, 

 especially in median and posterior regions, where consisting of simple 

 bulgings of the segments, which are, however, deeply margined an- 

 teriorly and laterally. The pore-bearing region of keels strongly 

 thickened and distinctly set off from the anterior portion of border, 

 the thickening elliptic in outline as seen from the side. Margin setiger- 

 ous. The slight caudal margin of keels not dentate. Tooth at an- 

 terior corner obsolete (see pi. 18, figs. 10, 11). Metazonites with a 

 transverse sulcus, behind which there are typically two rows of 

 tubercles or elevated areas, of which those of the posterior row are 

 the larger, these areas setigerous. In front of the sulcus the surface 

 is nearly smooth, being rather obscurely set off into six larger areas, 

 each of which bears a seta, the setae forming a single transverse series. 

 Caudal end of body represented in plate 18, figure 8. Sides of body 

 granular, more strongly so in anterior region. Pleural keels present 

 back to the eighth segment. Ventral plates about twice as wide as 

 long in the female, narrower in the male. All wholly lacking fur- 

 rows and special processes in the male. Legs slender, with tarsus 

 proportionately long and the two preceding joints short, as shown in 

 plate 18, figures 10 and 11. Last ventral plate liroadly subtriangular, 

 with the sides convex, a little notched on each side opposite base of 

 seta (pi. 18, fig. 9). Anal valves with mesal borders very strongly 

 elevated; surface longitudinally rugose. 



Gonopods of male as represented in plate 19, figures 1-3. 



Length, male, about 21 mm.; width, 2 mm. Length of a female, 

 about 25 mm. ; width, 2.5 mm. 



Locality. — Guatemala : San Rafael, one male and two females 

 (O.F.Cook, June 4, 1914). 



Type.— Cat. No. 849, U.S.N.M. 



