ISOFODS OF NORTH AMERICA. 



585 



1O1. Genus TYLOS Latreille. 



With characters of family. 

 Only genus. 



ANALYTICAL KEY TO THE SPECIES OF THE GENUS TYLOS. 



a. Terminal abdominal segment triangularly produced, with apex rounded. Ven- 

 tral plates or inferior processes of the fifth abdominal segment meeting in the 



median ventral line. Color white Tylos niveus Budde-Lund 



a' . Terminal abdominal segment quadrangular; posterior margin straight, not pro- 

 duced. Ventral plates of fifth abdominal segment not meeting in the median 

 ventral line. Color light brown with black spots. 



Tylos latreilli Audouin and Savigny 



TYLOS NIVEUS t Budde-Lund. 



Tylos niveus BUDDE-LUND, Crust. Isop. Terrestria, 1885, pp. 278-279. RICHARD- 

 SON, Proc. U. S. Nat. Mus., XXIII, 1901, p. 561; Trans. Conn. Acad. Sci., 

 XI, 1902, p. 301. 



Localities. Key West, Florida; Bermudas. 



Body oblong-ovate, convex, contractile into a ball, very minutely 

 and densely punctate, and covered with hairs, especially at the sides. 



Eyes small, composite, occupying a 

 fourth part of the width of the head; about 

 30 ocelli. 



First pair of antennse composed of one 

 article, immovable. 



Second pair lost in the specimen. Front 

 of head not separated from the epistome; 

 epistomal shield subtetragonal, becoming 

 narrow anteriorly, reflexed; clypeus large, 

 tretragonal, a little impressed transversely. 



The first segment of the thorax with the 

 lateral margin deeply sulcate; epimera of 

 the two following segments small, rounded, 

 subtriangular, a little excavate anteriorly. 



The fifth segment of the abdomen with 

 the inferior processes strong, tetragonal, meeting in the middle; the 

 fourth segment with the processes small, oblong, narrow; the third 

 segment with the epimera minute; the terminal segment convex, 

 extending a' little beyond the parallel epimera of the preceding seg- 

 ment. The uropoda form a rounded operculum, becoming narrower 

 anteriorly. 



Color white. 



Length 13 mm. Width 5.5 mm. Height 3 mm. a 



The above description is adapted from the following one of Budde-Lund's: 



Oblonge ovalis, convexus, in globum contractilis, minutissime et dense punctatus, 

 prsesertim ad latera setigerus. 



Oculi minores, compositi vel congregati, quartam partem capitis latitudinis possi- 

 dentes, corneulae vel ocelli circiter 30. 



Antennse exteriores . 



FIG. 645. TYLOS NIVEUS (AFTER 

 DOLLFUS). a, HEAD WITH ANTENNA. 

 6, LAST TWO SEGMENTS OF ABDOMEN. 



(ENLARGED.) 



