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BRITISH SPECIES 



351 



lobe with apex somewhat narrowed and carrying a sharp inner tooth. Anal 

 pyramid very long (longer than segs. 9 + 10) (A. imperator) 1 . 



Subfamily Corduliinae. Larva of type in fig. 38. Mask spoon-shaped 

 (fig. 32 o), the teeth of the distal border in the form of large crenations. 



Genus Oxygastra. Abdomen with no dorsal spines, but with fairly large 

 lateral spines on segs. 8 9. Crenations of mask very large, one-third as 

 high as wide, each carrying 14 or 15 short bristles (O. curtisi). 



Genus Cordulia. Abdomen with small dorsal spines on segs. 5 9, rather 

 small lateral spines on segs. 8 9. Legs very long; hind femur reaching 

 to seg. 8. Crenations of mask medium, one-fourth as high as wide, each 

 carrying 4 or 5 short bristles (C. aenea). 



a 



Fig. 180. Supracoxal armature of prothorax in larvae of Aeschna. a, Ae. grandis 

 Linn.; b, Ae. juncea Linn.; c, Ae. mixta Latr. ; d, Ae. cyanea Miiller; e, Ae. 

 isosceles Miiller. After Lucas and Cabot. 



Genus Somatochlora. Somatochlora metallica. Abdomen with very large 

 dorsal spines on segs. 5 9, small lateral spines on seg. 8. Hind femur reaching 

 to seg. 7. Crenations of mask medium, one-fourth as high as wide, each with 

 10 bristles. 



S. arctica. Abdomen with neither dorsal nor lateral spines. Hind femur 

 reaching only to middle of seg. 6. Crenations as in S. metallica, but with only 

 5 bristles on each. 



Subfamily Libellulinae. Tribe Libellulini. Larva of type in fig. 36 F. 

 Mask spoon-shaped (cf. fig. 32 N), the teeth of the distal border forming 

 small flattened crenulations. 



Lateral abdominal 

 Length spines 



23-5 8, moderate; 9, small 



Species 

 Libellula quadrimaculata 



fulva 



Orthetrum coerulescens 

 cancellatum 



21 

 21 



16 

 23 



8 9, large, bent 



8, rudimentary; 9, nil 



Dorsal abdominal 

 spines 



5 7, small ; 8, moderate ; 



9, nil 



6 9, large 



8, moderate ; 



5 7, small ; 

 9, nil 



very small, bent, on 8 9 7, rudimentary ; 8, nil 

 small, on 8 9 ,, 



In addition, L. depressa can be distinguished by having the crenulations 

 of the lateral lobe of the mask about one-fifth as high as wide ; in all the others 

 they are excessively flattened down. 



1 Lucas describes and figures this larva as having the appendix dorsalis 

 notched at tip, and nearly as long as the cerci. His, however, says that this organ 

 is truncated ("gerade abgeschnitten") and barely half as long as the cerci ! 



