282 



Scientific Proceedings^ Royal Dublin SocieUi. 



short and feeble. The mouth-hooks are remarkable on account of their 

 lateral direction, their sharp bifid tips pointing outwards instead of down- 

 wards ; tlie strong and prominent basal fulcral processes, which give 

 attachment to tlie biting muscles, are also directed outwardly. Between 

 the mouth-hooks tliere projects forward a sliarp and prominent median spine 

 (figs. 31, 32, 33, 35, M). This is not attached, as Glaser ('13, p. 31) states, 

 «'aiif einem kurzen Querbalken," but is the prolongation of a pair of slender 



Pa.^ 



Mouth armature of Larva of Horse-bot Fly [Gaslrophilus eqni). 



A, ventral, and B, lateral views of pharyngeal sclerites (Ph.), Hypostomal sclerites (Ho.), 



Mouth-hooks (H), and Parastonml sclerites (Pa.), x 32. 



2Mrastomal sclerites (fig. 33, pa.) which lie dorsal to the pharyngeal 

 sclerites; between these parastomals the dorsal pharyngeal wall is feebly 

 tliiekened, presenting the appearance of a median pointed process directed 

 backwards. It is of much interest to compare this condition witli that of tlie 

 first-stage Blowfly maggot described by Lowne ('90, fig. 9, 1), in which there 

 is a strong median downwardly curved tootli formed also as the prolongation 

 of a pair of parasternal sclerites ; in the young Calliphora maggot, however, 

 the paired mouth-hooks are very feeble. Another instructive comparison is 

 to be found in the well-known Bot-maggot (the larva of Qas(ro2)/dhis equi) 



