xxxiii, '22] ENTOMOLOGICAL NEWS 165 



A New Milliped of the Genus Polyxenus from the 



Florida Keys. 



By RALPH V. CHAMBERLIN, Cambridge, Massachusetts. 

 In January, 1919, Dr. Paul Bartsch took a Poly.vcnus either 

 emerging from or taking refuge in the breathing pore of a 

 Cerion on the Tortugas. Florida. The specimen apparently 

 represents a new species which is here described. 



Polyxenus bartschi, sp. nov. 



The type specimen is not fully adult, being in the stage pos- 

 sessing eight pairs of fascicles of lateral setae. It is in the 

 Museum of Comparative Zoology, Cambridge, Massachusetts. 



The dorsum is marked with a hroad longitudinal stripe along each 

 side and a narrow median pale stripe. Setae of caudal pencil white as 

 usual. 



The eight articles of the antennae present and apparently fully devel- 

 oped ; the third, fourth, fifth, sixth, seventh and eighth articles respec- 

 tively .04, .058, .05, .1, .05 and .02 mm. long, with the corresponding 

 widths being .046, .05, .05, .058, .05 and .03 mm. The precise number of 

 ocelli in the patch on each side of head was not determined because of 

 the obscuring pigment. 



The major and more numerous setae of the head are relatively slender 

 and flexible with the teeth long, slender and numerous, subdensely 

 appressed ; the naked terminal lobe distally a little rounded. There 

 are fewer short scales which are only four times, or less, as long as 

 thick and are half or less the length of the long setae; their teeth are 

 coarser and fewer in number. 



The setae of the lateral fascicles are similar to the major ones of 

 the head, hut are mostly less flexible and with the lateral teeth usually 

 fewer. 



The setae across the tergitcs are in general similar to the shorter 

 setae or scales of the head ; mostly with seven or eight teeth in each 

 lateral series, the terminal lobe with distal margin convex; mostly 

 between four and five times longer than wide. 



In the caudal pencils there are two principal types of setae. There 

 arc, firstly, the mostly peripheral setae very similar to those of the lateral 

 fascicles excepting for their greater length. The greater portion of 

 the pencils, however, is composed of much finer setae of \arying length 

 which have subspatulate distal ends which are usually a little Ix-nt. 

 X'one of the characteristic hooked setae, such as occur in /'. liuinnis 

 and /'. fiisciciilutus. are present. 



Length, without caudal pencil. 2 mm. Length of caudal pencil, .66 

 mm. Length of maximum setae of head, .2 mm.; of setae m' anterior 

 paired fascicles, .23 mm.; of posterior paired fascicles, .28 mm.; of the 

 dorsal setae or scales up to about .1 mm. 



