586 PROCEEDINGS OF THE NATIONAL MUSEUM vol. in 



Propleuron: Polished, with distinct punctures only in depression; 

 prosternal carinae low, narrow. 



Mesopleuron: Evaporatorium large, lateral margin gently convex; 

 polished area impunctate. 



Sternites: Shining, impunctate. 



Legs: Moderately long, 



Terminalia: Apical margin of genital capsule slightly sinuate, not 

 flared, surface impunctate; gonostylus as illustrated (fig. 264). 



Length of body: 7.20(6.90-7.20). 



Female: Similar to male but without "fold" in side margin of 

 pronotum and scutellum with more numerous punctures extending 

 onto apical half. 



Head: Length-width ratio, 1.13(1.10-1.16) : 1.69(1.69-1.70); inter- 

 ocular width, 0.95(0.93-0.98). Antennal segments: I, 0.38(0.36- 

 0.40); II, 0.44(0.43-0.46); III, 0.49(0.46-0.53); IV, 0.64(0.63-0.65); 

 V, 0.80(0.80-0.80). Labial segments: I, 0.60(0.60-0.60); II, 1.03 

 (1.03-1.03); III, 0.74(0.73-0.76); IV, 0.58(0.56-0.60). 



Pronotum: Length-width ratio, 1.88(1.82-1.95) :3. 64(3. 63-3. 66). 



Scutellum: Length-width ratio, 2.76(2.66-2.86) :2.23(2. 13-2.28). 



Length of body: 7.11(7.02-7.20). 



Type data. — The type male (Stock) is labeled "Rio," and was 

 reported by StS-l to have come from Rio de Janeiro, Brazil. 



Specimens studied. — 2 males, 2 females. 



Brazil: Santa Catarina: Corupa, October 1945, A. Mailer, 1 female (AmM). 

 Nova Teutonia, Oct. 6, 1944, Mailer, 1 female (JCL); Feb. 22, 1949, Mailer, 

 1 male (JCL). Rio de Janeiro: "Rio," type specimen, 1 male (Stock). 



Discussion. — The type specimen was available for study through 

 the kindness of Dr. Rene Malaise. It proved to be in an excellent 

 state of preservation, lacking only antennals II-V on one side and 

 IV and V on the other. 



The peculiar "fold" which occurs in the side margin of male pro- 

 notum appears in only one other known species of cydnid, Dallasiellus 

 solitaria (Horv^th). The biological significance of this structure is 

 not apparent and as a taxonomic character it appears to be of no 

 more than specific worth, as americanus and solitaria are not espe- 

 cially closely related, other than generically, on other features. 



Signoret's illustration of the pleurae of this species is so inaccurate 

 as to suggest the possibility of an error in association of sketches. 

 His illustration of those structures ior foratus is reasonably similar to 

 that of americanus as determined in the present paper from a study 

 of Stal's type. 



