38 Transactions of the Society. 



through larval and pupal stages, from tie maxilla?. On making 

 some fresh dissections of the head of C. plumosus L., mounted with- 

 out pressure, I was able to make out very clearly the cardines of 

 the maxillae, and to see the connection with the palpi, thus proving 

 Mr. Hammond's point and the reliability of my rale. I have also 

 heads of C. dorsaiis, C. viridis Mcq., and G. riparius Mg., which 

 agree with C. p>lumosus. 



In many of the Tipulida? a special difficulty is encountered. 

 The cardines of the maxilla?, which in the very large majority of 

 species are so useful a guide, are replaced by two median apodemes, 

 one on the dorsal, and one on the ventral side. That on the dorsal 

 side thickens anteriorly and bifurcates, sending out symmetrical 

 arms to the sides, to which the four-jointed palpi are attached. 

 On examining this apodeme with high powers, a suture can easily 

 be made out, running down the centre, and obviously this part is a 

 fusion of the maxillary cardines. The ventral apodeme is without 

 lateral processes, but a suture is evident, and I homologise this 

 part with the mandibles. Tipula olcracea L. has a very imperfect 

 labium and hypopharynx, and the whole mouth-parts seem to have 

 undergone great changes (pi. V. fig. 11). The Ptychopterida? are 

 also of this type, but the cardines are separate. Urioptera tceni- 

 onota Mg. has a well-marked labrum of the usual type in Diptera, 

 while an insect which Mr. J. H. Verrall places in the same family 

 (Limnobida?), the common Trichocera hiemalis Deg. has maxilla', 

 a ciliated hypopharynx and well-developed labium, and would be 

 placed in Group 2. 



In the Brachycera, the Stratiomida? have the trachea? well de- 

 veloped and numerous, but not occupying the whole space of the 

 paraglossa?, as in the Muscida? ; the palpi have two joints, and in 

 S. chameleon L. the palpifers can be differentiated ; the maxilla? are 

 very minute in this species, almost obliterated ; they are more 

 visible in Microschrysa polita L., but have quite disappeared in 

 Chloromyia formosa Scop. The labrum is rather formless, and I 

 have not seen a ciliated hypopharynx in any species (pi. VI. fig. 1). 



The Conopoda? have a specialised type of mouth-part, resembling 

 the Syrphida?, but having no maxilla?. In some species the labrum 

 is short, and the hypopharynx long ; the latter organ seems to find 

 its protection in the fold of the labium. In Conops quctdrifasciata 

 Deg. it is remarkable that only the rudiments of the maxillary 

 palpi are present, while the labial are wholly aborted. I know of 

 no exactly parallel case, but in Sepsis cynipsca L. the palpi are 

 exceedingly minute, but are labial, and remnants of the maxilla? 

 are present, two or three hairs marking the place of their palpi 

 (pi. VI. fig. 8). 



Group 4. — To determine the homologies of the mouth-parts in 

 Bibio requires a dissection of the parts, and a comparison with the 



