ii8 OHIO BKJLOGICAL SURVEY 



EXPLANATION OF PLATE IX. 



Figures i8i, 182, Microdon sp. 



Fig. 181 Ventral view of anterior end of larva of Microdon sp. showing the mouth- 

 parts; a, the marginal fringe; Zi, antenna; r, mandible-like mouth-hooks; 

 c/, t\ the tri-fid lower jaw; very much enlarged. 



Fig. 182 A dorsal view of larva of Microdon sp. showing general appearance, the- 

 marginal fringe, the reticulate ornamentation of the dorsum and the pos- 

 terior respiratory appendage, x 10. 



Figures 183-187, inclusive, Microdon iristis 



Fig. 183 E:npty pupariuni of Microdon tristis showing general sliape and appear- 

 ance; the orifice through which the adult emerged; the posterior respiratory 

 appendage, etc. x 5.5. 



Fig. 184 One half of the posterior respiratory appendage showing the arborescent 

 stigmatic pattern; (7, the circular plate; x 40. 



Fig. 185 Antero-dorsal view of posterior respiratory appendage, x 40. 



Fig. 186 Anterior pupal respiratory cornuum, which is pushed off with the oper- 

 culum; much enlarged showing the tubercles on its surface. 



Fig. 187 A small area of the surface of the pupal cornuum, highly magnified; showing 

 the appearance of the tubercle- like spiracles, each with a short piece of 

 its afferent trachea, visible thru the integuments. 



Figures 191- 194, inclusive, Mesogramma polita 



Fig. 191 The jaws of the larva as dissected from a pupariiim highly magnified 

 The rest of the mouth-parts could not be determined. 



Fig. 192 Lateral view of puparium of JM. polita, x 10, showing general shape; a, 

 the posterior respiratory appendage. 



Pift- 193 Antero-dorsal view of posterior respiratory appendage x 75; a, the most 

 dorsal of the spiracles which is short, its elevation rounded; b, the dorsal, 

 spiracular spine. 



Fig. 194 End view of the posterior respiratory appendage; magnification and let- 

 tering same as in Fig. 193; f, d, the two more ventral and elongate spiracles. 



