36 Transactions of the Society. 



parts, and he probably bites, and his individual misconduct is laid 

 to his brethren in general. 



Besides the ciliated hypopharynx, another reversion appears 

 occasionally in the males, rarely in the females. On the labium is 

 sometimes found a false joint, or a swelling which has the appear- 

 ance of a false joint. This is relatively on tbe same place as the 

 labial palpi are found in Dilophus, or the palpigers in Chrysops. 

 It is difficult of explanation, but it seems probable that it bears 

 some relation to the aborted labial palpi (pi. III. fig. 7). I have 

 preparations of the heads of C. pipiens, male and female, G. con- 

 color <J, G. fatigans <J, and Dinoccrites cancer <J, with this joint 

 well marked ; and in the cabinet at the British Museum (Natural 

 History) is a species, the males all having a hairy bulb at the same 

 spot (Limatus durhamii Theo., South America). 



Gorcthra emphasises the relationship between the "plumed" 

 and " biting " gnats, as it has a longer labium than most Chiro- 

 nomydse, with structures on the base of the paraglossa? similar to 

 those found in the same place in the Culicidse, a ciliated hypo- 

 pharynx, four jointed palpi, and broad stout maxillae (pi. V. fig. 6). 

 Geratopogon pulicaris L., one of the minute biting midges, lias a 

 labium very much the same shape as Gorcthra plumicornis F., long 

 fine maxilla?, a strong labrum, and a ciliated hypopharynx. The 

 structure of the mandibles is evident on the dorsal side of the 

 labium (pi. V. fig. 7). 



Rliyphus fenestralis Scop, and R. punctatus F. have typical 

 mouth-parts of this group, in character practically the same as 

 Psychoda ; the maxilla? are hairy, the palpi are four-jointed, the 

 hypopharynx is ciliated, and the trachea? of the paraglossa? fairly 

 well developed. The Bhyphidse are said to feed on the juices of 

 plants (pi. V. fig. 9). 



In this group, besides the EmpidaB, are two more families of the 



EXPLANATION OF PLATE V 



1. Tropin of Ptychorfa , phaltenoides L. Dorsal view. 



2. Tiophi of male Culex pipiens L. The mandibles are aborted, and the maxillce 



are in an atrophying slate. Dorsal view, 



3. Paraglossse of C. pipiens. Ventral view, showing chitinous processes at base, also 



found in Corethra plumicornis F. 



4. Hypopharynx of C. pipiens 6 , showing the ciliated tip. 



5. Troplii of Anopheles maculipennis Mg. Exceptional male, with complete mouth- 



parts ; the mandibles and maxillso are in an atrophying condition. 

 G. Tropin of Corethra plumicornis b\ Dorsal view. 



7. „ of Ceratopoqon pulicaris L. Dorsal view. 



8. „ of an undetermined Cecid. Dorsal view. 



9. ,, of lihyphus fenestralis Scop. 



10. „ of Chironomus plumosus L. Dorsal view. 



11. Dissection of the dorsal apodeme of lipula oleracea L. Showing the palpi 



attached, and the median suture of the fused stipites andcardines. 



