The Mouth-parts of the Nemoeera, etc. By W. Wesche. 31 



it is on the ventral side of the labium, but it is an important part 

 of the trophi. All these parts are found in the various families of 

 Diptera (pi. III. fig. 1). 



I do not include the Pulicidre in this classification, as good 

 authorities place them in an order by themselves, Siphonaptera . 

 But there are so many points of general affinity that I give a 

 figure of the mouth-parts, which are however on a first view very 

 far removed from the type in Diptera. The absence of any labium 

 or paraglossa? at once differentiates them. These insects are pro- 

 vided with two sets of palpi, both four-jointed, the maxillary on 

 the maxilla and the labial, higher up on the head, and having 

 some analogy to the situation of the labial palpi in the Muscidse. 

 The labrum is absent or very minute, but the hypopharynx is well 

 marked ; the maxilke have undergone a curious transformation, 

 and the mandibles are scales on either side of the head (pi. I. 

 % 2). 



Group 1. — The Simulidse have four-jointed maxillary palpi, 

 and differ from the females of the genus Culex which have 

 apparently only two joints, though the males have four. The 

 hypopharynx in the Simulidte is ciliated at the extremity, and 

 under it is a curious wrinkled membrane which may possibly be 

 the epipharynx ; but this part is so minute that it is impossible 

 to be certain, and I only note it as a possibility. The mandibles 

 are provided with very beautiful serrated edges, and the maxillfe 

 are even more complicated, as they are provided with a double 

 row of sharp teeth. These insects are keen blood-suckers (pi. IV. 

 fig. 7). 



In the Culicida? are curious differences : — (1) The genus Corethra 

 though possessing the wing of a biting gnat, has a much less 

 modified mouth-part; it is without mandibles, and the maxilla? 

 are broad, minutely pubescent and unfitted for piercing purposes. 

 (2) The mouth-parts of the sexes are different in the other genera 

 (pi. II. fig. 5). 



Since the mosquito has been found to be the host of the 

 malaria parasite, this family has been much studied, and a number 

 of new species has resulted in several fresh genera. Mr. F. V. 

 Theobald has kindly placed many specimens at my disposal, and 

 I have examined the following species with a view of finding 

 specific or generic characters in the mouth-parts. 



Culex pipiens L. 



C.fatigans Wied. 



C. annulatus Schrk. 



C. concolor Des. 



Stegomyia fasciata F. 



Mizorhynchus barhirostris "Walk. 



Thcobaldia spathijKiIpus Eond. 



