272 Scientific Proceedings, Royal Dublin Society. 



14, vi., vii., viii., ix.) ; and we believe that the tenth segment is also represented, 

 by the tip of the terminal dorsal plate. The whole organ wlien fully 

 protruded measures 12 mm. in length in H. bovis, and 8 mm in H. lineatimi; 

 the corresponding figures on Plates XXII (bovis) and XXIII (Uneatum) are 

 drawn to the same scale. 



In H. bovis the sixth segment has an elongate dorsal sclerite or tergum 

 (fig. 5, vi.) rounded in front, slightly broadened and truncate behind, 

 and a sternum (fig. 6, vi.) shorter than the tergum, and broader in front 

 than at its hinder edge, which is feebly emarginate. In IF. Uneatum the 

 tergum of the sixth segment (figs. 13, 14, vi.) is deeply cleft in front and 

 much broadened behind, extending to the lateral regions of the segment ; the 

 sternum (fig. 15) is parallel-sided and relatively broader than that of IT. bovis. 



The seventli segment has in both species two tergal sclerites ; possibly 

 the anterior cleft iu the sixth tergum of H. Uneatum indicates a stage leading 

 to this condition. The seventh tergal sclerites in H. bovis (fig. 5, vii.) are 

 relatively longer and more slender than those of H. Uneatum (fig. 14, vii.). 

 In H. bovis, there is a single seventh sternal plate (fig. 6, vii.) slightly 

 tapering to the hinder edge, which is feebly emarginate ; in H. Uneatum the 

 seventh segment has two elongate sternal sclerites almost in contact in the 

 median line (fig. 15). 



The eighth segment is much shorter than those preceding it, and has two 

 tergal plates in both species (figs. 8 and 16, T. 8) with broad anterior 

 and pointed hinder ends ; in H. Uneatum (fig. 16) tliese plates differ slightly 

 in shape from the corresponding structures in H. bovis (fig. 8). The sternal 

 sclerites are in both species a pair of long plates, sinuate in H. bovis (figs. 8, 

 11, St. 8), narrower and straight in M, Uneatum (figs. 16, 18, St. 8). The 

 hinder extremities of these plates are rounded processes (figs. 8, 11, 16, 18, 

 P. 8) beset with short sharp spines in M. bovis. These are described as 

 " blattartige Fortsatze " in Glaser's recent account of the Warble-fly's 

 ovipositor ('13, p. 22). It is barely possible that they may represent the 

 genital processes or gonapophyses of the eighth abdominal segment which 

 are characteristic structures of a typical insectan ovipositor such as is found 

 among the Orthoptera, Hemiptera, and Hymenoptera ; but there is nothing 

 in their appearance to suggest that they are anything but prolongations 

 of the sternal sclerites. 



Tliese processes form the ventral boundary of the tip of the ovipositor. 

 Dorsally is to be seen a strong tergal sclerite, broad in front, constricted 

 towards the middle, and widening again at the hinder end ; in H. Uneatum 

 (figs. 16 and 17), it is relatively narrower and more constricted tiiau iu 

 H. bovis (figs. 8 and 10). The front part of this sclerite (T, 9) certainly 



