PHILIP P. CALVERT 337 



the following Odonata were observed: Brechmorhoga mpax cro- 

 cosema Ris, Epigomphus suhohtmus Selys, Paltothemis linealipes 

 Karsch, Hetaen'na cruentaia Ramb., Argia extranea Hagen and 

 Cora chirripa Calvert. A marked similarity in color and manner 

 of flight between the Brechmorhoga and the Epigomphus was 

 noted. They were found at the same spot in the stream. The 

 resemblances observed were: 



The approximately equal length of body, the abdomen widest at or near 

 its hind end, the blue (Epigomphus) or bluish-green (Brechmorhoga) eyes, 

 the thoracis pattern — dai'k brown with pale oblique bluish or greenish stripes, 

 the abdomen dark brown with bluish (Epigomphus) or greenish (Brechmo- 

 hoga) longitudinal markings at the bases of segments three to five or six, 

 the seventh segment with a more conspicuous pale marking than on any other 

 part of the body. 



The differences other than those of taxonomic value are: 

 The more robust form and wider wings of Brechmorhoga, the widening of 

 the abdomen on segments eight to ten in Epigomphus, on six to seven in 

 Brechmorhoga; the metallic green of the frons of Brechmorhoga, pale blue in 

 Epigomphus, the wider pale stripes on the thorax of Brechmorhoga, the pale 

 mark of abdominal segment seven in Brechmorhoga deep yellow, in Epi- 

 gomphus pale blue. 



While the manner of flight is similar, Brechmorhoga stays 

 longer on the wing and poises longer in the air, while Epigomphus 

 tends to alight more frequently. E. subobtusus and other species 

 of its genus curl the hind end of the abdomen ventrad very often 

 when fljdng about. 



When referring to these observations in 1917 we pointed out 

 that: "There was nothing in this case, however, to suggest that 

 the resemblance offered a means of defense to either species 

 against enemies." 



The following notes are based on the material listed antea, page 32(3. and 

 on two males three females from Cayuga, Guatemala, April 25, May 3, 8 

 and 28 taken by Messrs. Schaus and Barnes, included in the paper of 1919. 



Pale color of the dorsal surface of the frons not separated into two spots 

 right and left in all five males and the Juan Vinas female; so sei)arated in 

 three females, that of April 25 being uncertain. 



Metepimeron with a brown stripe as described for E. subsimilis, not reach- 

 ing the whole length of the sclerite. 



Abdominal segment two with a longitudinal, mid-dorsal, yellowish-^ strijie 



23Color as seen in the dried specimens. Compare the statements given 

 above for the hving colors. 



TR.\NS. A.M. ENT. SOC, XLVI. 



