Some Palaearctic species of Cordulegaster. 283 



(Mon. des Gomphines, pp. 599-600.) 



The principal characters of C. bidentatus are — 



Frons yellow with a very strong transverse frontal line ; nasus 

 very narrowly margined with blackish at the junction with the 

 rhinarium and also with two blackish spots; rhinarium black; 

 labruni with black margin all round and a strongly marked virgule. 

 Occiput above black with blackish hairs; behind yellowish, not 

 swollen, nearly bisected with a darker line. 



Prothorax with interrupted median and posterior line. 



Thorax : no humeral dot ; lateral intermediate band variable 

 usually much reduced sometimes to a mere point. 



Abdomen : 1st segment with an oblique lateral spot not descending 

 to ventral suture; 2nd segment with a narrow dorsal yellow band 

 occupying about ^ of segment, almost isolated from the large anterior 

 lateral yellow spot (this band continued without interruption in ?) ; 

 lunules rather large, cut off from lower posterior spot; bands of 

 segments 3 to 8 variable, mostly rather narrow, those of 6, 7 and 8 

 usually more so than the others, usually all interrupted by the dorsal 

 arete, 7 and 8 at least reaching the ventral suture. Traces of yellow 

 on the anterior part of segment 9. Posterior lunules on 2, 3 and 4. 



Actual distribution not quite ascertained. Ris (Siiss- 

 wasserfauna Deutschlands, Odonata, p. 23) says west and 

 southern Europe. It occurs in Herzegovina and perhaps 

 further east, it may be, even extending to Asia Minor. 

 Calvert (Proc. Acad. Nat. Sciences Philadelphia, 1898, 

 p. 152) records it from Kashmir, but his insect is certainly 

 not the typical form. Examples from Digne (Basses Alpes) 

 are very similar to Swiss specimens, showing no variation 

 corresponding to the southern characters displayed by 

 C. annulatus in the same locality. A male from Mostar 

 in Herzegovina is also very similar, the yellow bands being 

 only a little stronger, with traces of yellow even on segment 

 10. Females from Jablonica have the black margin of the 

 labrum exceedingly broad, so that the virgule practically 

 touches the anterior margin, thus dividing the yellow of 

 the disc in two. De Selys, as mentioned above, says the 

 virgule touches the anterior margin, but this is not always 

 the case. 



