PROCEEDINGS OF THE NATIONAL MUSEUM. 57 



Lateral carinas not as broad as in P. acus, a usual sexual difference, 

 but the posterior corner is in all cases less produced than in that spe- 

 cies, and the large tooth of the posterior corner is rounded and not 

 prominent, while the next mesad on the posterior margin is conspicu- 

 ously enlarged, on the anterior segments more especially. 



Eepugnatorial pores located as in P. acus, but the poriferous process 

 shorter and less distinctly capitate. 



Last segment distinctly shorter than in P. acns; the superior lateral 

 tubercle smaller. 



Preanal scale regularly semicircular, medianly abruptly mucrouate; 

 the setigerons tubercles distinctly less prominent than in P. acus. 



Legs much shorter, a usual sexual difference. 



Genitalia oblong, large, and very prominent, with the ventro-caudal 

 aspect showing three distinct teeth on each side. 



Color in alcohol bright brown, darkest on anterior segments and in 

 the sutures and transverse sulci of the dorsal surface of the segments; 

 ventral surface, legs, antenucT, and margins of carina? nearly Avliite. 

 The color is almost exactly the same as in P. acus, but the shades are 

 much lighter. 



Length, 28 mm.; width, 3,3 mm. 



Locality.— VciYn (Schulz). A single female specimen in the Berlin 

 Museum. As stated above, this may 'prove to be the female of P. acus, 

 but the differences are such that the analogy of other Polydesmoidea 

 makes this improbable. 



EXPLANATION OF PLATE I. 



Friochsmns acus, male. 



Fig. 1. First five segments, dorsal view. 



2. Segments 7 and 8, dorsal view ; the small granules ai-e somewhat too numer- 



ous on this figure. 



3. Gnathochilarium. 



4. Antenna. 



5. Apex of antenna, showing the arrangement of the olfactorj' cones, sub- 



diagrammatic. 



6. Tenth segment detached. 



7. Leg of pair 31. 



8. Leg of pair 3. 



9. Leg of pair 9. 



10. Genitalia, ventral view. 



11. Genitalium, lateral view. 



12. Apex of larger ramus of genitalium. 



13. Segments 16-20, dorsal view. 



14. Apex of last segment, apico-ventral \iew. 



15. Segments 18-20, ventral view. 



16. Same, lateral view. 



17. Last segment, dorsal view, more magnified. 



18. Leg of pair 6. 



19. Apex of same. 



