Odonatafrovi Arr/pntina. 291 



Family AgrionidaB. 



Subfamily AoRioyijfx. 



Acanthayrion interruptum, Sclys. 



4 (?, 5 ? , Estaticia Tecka, S.W. Chubut, i. 1920. 



As shown by the structure of the anal appendages of the 

 male sex, this Patagotiian material belongs^ not to the form 

 from Buenos Aires to which Ris has given the subspecific 

 name of honariense, but to the typical form of the species, 

 as originally described from Valparaiso, and subsequently 

 recorded from other parts of Chile, as well as from the 

 Patagonian Territory of Neuquen. This species is the geno- 

 type of Cyanallayma, Kennedy (Ohio Journ. Sci. xxi. p. 87, 

 1920). 



Acanthagrion cheliferum, Selys. 



1 S, Isla Ella, -Rio Parana, x. 1919. 



This specimen is badly discoloured, but seems to agree in 

 its essential characters, both morphological and otherwise, 

 with De Selvs's original description of a series of males from 

 Brazil (Bulf. Acad. Belg. (2) xli. p. 319, 1876). The lower 

 anal appendages, hoMCver, are shorter and more conical 

 than those figured for the species by Ris (Hamburg. Magal- 

 haen. Sammelr. vii., Odonaten, p. 12, fig. 7, 1904'), and 

 appear to be more in accordance with what De Selys says of 

 those structures, " rapproches en forme de deux tubercules 

 coniques." The species has been previously recorded from 

 the neighbourhood of Buenos Aires. A. cheliferum is, 

 perhaps, to be included in the genus Cyanallayma (Kennedy, 

 loc. cit.). 



Acanthagrion ambiguum, Ris. 



16 c? , 7 ? , Isla Ella, Rio Parana, x. 1919. 



A very small species, exhibiting affinities with several 

 different genera, and whose true systematic position is 

 somewhat uncertain. It was originally described from the 

 neighbourhood of Buenos Aires (Hamburg. Magalhaen. 

 Sammelr. vii., Odonaten, p. 13, 1904), and Calvert has 

 recorded it from Paraguay (Ann. Carnegie Mus. vi. p. 176, 

 1909). Of the three forms of the female distinguished by 

 Ris, only ? c is represented in the |)resent collection. That 

 is the form in which the pale coiulition of the head and 



