ANATOMY OF THE GOUT-FLY OF BARLEY. 809 



With the exception of the above points the first instar is a 

 miniature replica of tlie third. 



The Second Laroal Instar is identical in external anatomy, 

 except for size, to the third. A mature second instar is only 

 recognisable from a young third insta.r hj the fact that in the 

 former there can be seen the developing spiracles and cephalo- 

 pharyngeal skeleton of the third instar alongside those of the 

 ■second instar itself. 



IViC Egg (text-fig. 13) is approximately cylindrical with its 

 ventral surface flattened and its dorsal surface strongly convex 

 transversely and slightly so longitudinally. The egg nanows 

 slightly at both ends. There is a definite polarity of the egg,s 

 which are ahvays laid on the leaf of the host-plant in a certain 

 way. The anterior end, which points towards the apex of the 

 leaf, is slightly dorso-ventrally flattened and very slightly truncate 

 at the apex. The posterior end is evenly rounded and not dorso- 



Text-fignre 13. 



0-1 mm. 



Anterior t ' ' (i-^mw. ' ' Posterior 



C. tteniopus. A. Oiitliiio drawing of egg viewed dorsally. 

 IJ. Outline of pits on dorsal surface seen at a higher magnification. 



ventrally flattened. The upper surface and sides of the egg are 

 ornamented with small polygonal depressions set in longitudinal 

 rows, which may or may not extend the whole length of the egg. 

 The ridges separating two adjacent depressions in a row are not 

 quite so high as the longitudinal ridges which separate adjacent 

 rows. The ventral surface of the egg bears a few longitudinal 

 rounded ridges. The egg is firmly attached to the plant upon 

 which it is laid by a transparent cementing material. JSTo micro- 

 pylar apparatus has been observed. 



Host- Plants. 



As the question of the host-plants of Chlorops will be con- 

 sidered in detail in a later paper, it will be sufiicient to state 

 here that Agropyritm { = Triticum) repens is the only wild grass 

 in which the larva has been found up to the present. 



