1921] NATURAL SCIENCES OF PHILADELPHIA. 245 



ate at caudal margins with cinnamon-buff, a medi-olongitudinal band 

 of this color on mesonotum and metanotum, the abdomen with 

 broadly projecting portions of tergites paler, tessellate, and with 

 a concentric paler tessellate area, this inclosing the median portion 

 of the median segment and first two tergites, which area is of 

 the darker ground color, the tergites each with a fleck cinnamon- 

 buff between the lateral and median areas. 



Without much larger series than have ever been assembled, the 

 separation of many of the species of such genera as the present, 

 Phoraspis, Paratropes and Tribonium, is a most difficult problem. 

 The differences shown by the forms recognized by us as Tribonidium 

 monasticum, transversum and amplum, may indicate full specific 

 distinction, geographic racial differentiation or, indeed, mere in- 

 dividual variation in a single exceptionally plastic species. Addi- 

 tional material with full data would throw much light on this prob- 

 lem, if not definitely solving it. Color differences such as are 

 shown and different degrees of structural and tegminal and wing 

 modification are sometimes unimportant, sometimes of great diag- 

 nostic value. It is clear that in genera such as the present, where 

 limb armament is so greatly reduced and the genitalic features may 

 show generic but not specific differences, we are forced to weigh 

 the recognizable differences and to form conclusions as to their 

 value in each individual case, without the degree of assurance poss- 

 ible when familiar with other groups and working with even unique 

 individuals of many of the species. 



BLABERINAE. 



Petasodes monffeti (Kirby) Plate XIII, flgiu-e 4. 



1817. B[latta\ mouffeti Kirby in Spence, Introd. Ent., II, p. 329. [Brazil- 



1818. B[latta\ moiiffeti Kirby, Trans. Linn. Soc, XII, p. 448. [Brazil.] 



Tijuca, Rio de Janeiro, Brazil, 19,2 juv. 9 . 



Kirby first proposed this name for a species he recognized as 

 having large pul villi and no arolia between the tarsal claws, referring 

 to Mouffet 's figure published in 1634. That figure is extremely un- 

 satisfactory, though we do not agree with Burmeister in considering 

 it to resemble more closely Leucophaea maderae (Fabricius) than 

 the species now assigned to the genus Petasodes. In 1818, Kirby 

 has given a description of the insect, decidedly more comprehensive 

 than many of that time, and we follow Burmeister, but not sub- 

 sequent authors, in recognizing mouffeti as a distinct species. 



Compared with females of the other species of the genus before 

 us, the present female is seen to be decidedly narrower,with prone- 



