374 ME. WALTEK WESCHE ON THE GENITALIA OP 



Analogies. 



Gi^eat Apodeme. — (1) It is present in its paired form in several (judging from the 

 geological record) of the oldest families (TipulidsB and Tabanidse). 



(2) It is present in its fused condition in tlie Cyclorrapha, only to be found in the 

 Oolite, whereas the Nematocera and the Brachycera date from the Lias, or, in simpler 

 language, it is found in the fused condition in the younger families, but still retaining 

 traces of its former state. 



(3) It performs the functions of an apodeme, governing the movements of the 

 central organ. 



(4) It is situated at the base of the central organ. 



Submenttwi (fig. 137). — (1) This, when part of the second maxillae, consists of the 

 stipites and cardines of paired organs, the posts or levers, and hinges of a more or less 

 complicated mechanism. 



(2) It is fused in insects Vika Feriplaneta, or in the Cyclorrapha, but still retains traces 

 of its paired state. 



(3) It performs the functions of an apodeme, governing the movements of the central 

 organ. 



(4) It is situated at the base of the central organ. 



A plate from the ovipositor of an undetermined Asilid from Queensland, that has 

 already been alluded to, is remarkably like in general outline and some points of 

 structure to the submentum (fulcrum) in Diptera. This I consider is homologous with 

 the apodemes, and consequently represents the submentum. 



Lahrum and Fo7'cipes superiores. — Evidence in favour of another part is also forth- 

 coming — the identification of the labrum as the representative of the fused forcipes 

 superiores. I have repeatedly mentioned the hairy nature of these last-named parts, 

 which will now be seen to have a connexion with the matter under discussion. I will 

 state my reasons at length for my selection. 



HypopJiarynx (1).— There is only one unpaired chltinous organ in the mouth-parts, the 

 hypopharynx, situated immediately behind the central organ, the labium. 



Spinus. — There is only one unpaired cUtinous organ in the genitalia, the spinus 

 titillatorius, situated immediately behind the central organ, the penis ; therefore one 

 represents the other. 



Composition of Labrum (2). — Covering and next to the hypopharynx is the labrum, an 

 obvious fusion of paired organs, with often a cleft at the extremity, and always a 

 median suture and symmetrical rows of bristle-cavities (PI. 30. figs. 129, 130) ; probably 

 a fusion of the lacinia? of the maxillae, the true labrum being the mouth-edge. This 

 exists as a separate part in the Ephydridte ; Parydra coarctata, Tall.*, shows it 

 jiarticularly well. 



* See Journ. Roy. Micr. Soc, 1904, pi. 8. fig. 7, where, however, I mark the part as ihe Clypeus, following 

 the usual practice. 



