Vol. Xxii] ENTOMOLOGICAL NEWS. 449 



Studies on Costa Rican Odonata. 



III. Structure and Transformation of the Larva of Mecistogaster 



modestus. 



By Philip P. Calvert, Ph.D., University of Pennsylvania, 

 Philadelphia, Pa. 



(Plates XVII-XLX) 



The early stages of this long-bodied dragon fly whose dis- 

 covery and habits have been described in the News for Novem- 

 ber, pages 402-410. furnish the following 



Description of the Larva of M. modestus. 

 Material Studied: 



(a) From Juan Vinas, Costa Rica. 



Total length Body length 



including caudal excluding 



No. gills. caudal gills. 



48 9 larva (gills lacking) 1 1 mm. 



49 5 " 15 mm. 11.5 " 



54 5 " 10.5 " 7 



55 $ exuvia (gills lacking) 21.5 " 



56 S partly transformed 



57 9 exuvia 25 mm. 19.5 " 



58 9 larva 23 " 19 " 



58 9 exuvia (gills lacking) 



59 9 exuvia " " 19.5 " 



61 $ exuvia of March 13-16.... " " (in fragments) 



I $ larva 25.5 " 21 mm. 



29 " 24 " 20 " 



3 9 " 17-5 " M " 



9 exuvia of April 28 (gills imperfect) (distorted) 



9 " " May i 23.5 mm. 19.5 mm. 



$ " " Dec. 17 (gills lacking) (distorted) 



loi ? larva recovered from crop of 



No. I (in fragments) 



(b) From Orosi. Costa Rica, March, 191 1, collected by Sr. C. Picado 

 T., and forwarded by Prof. J. F. Tristan. 



9 exuvia dimensions as above, 20.5 and 18 mm. 

 $ exuvia dimensions as above. 23 and 19.5 mm. 



(c) From Cordoba, Mexico, April, 1908, bred by Mr. F. Knab. 

 (See Calvert, 1910.) 



9 exuvia (distorted). 



