G38 Mr. L. Gr. Saunders on the Larvcij 



Systematic Position. 



It will be seen from the foregoing description that the 

 resemblance of Orphnephila larvae to the Chironomids is 

 merely superficial, being based on the long slender body 

 with anterior and posterior pseudopods — characters which 

 may readily be acquired by convergence. The more funda- 

 mental characters, such as the mouth-parts and respiratory 

 apparatus, show no such relation. The fact that the larva is 

 amphipneustic and the pupa peripneustic is alone sufficient 

 to exclude Orphnephila from the Chironomidse, for, despite 

 Brauer's (1883) specification '^ amphipneustisch oder mit 

 TracheenbJasen oder Kiemen,'-' no Chironomid larva has ever 

 been found with functional spiracles. Minute non-functional 

 spiracles occur on the abdomen of probably all Chironomid 

 pupae (Bause 1915, Potthast 1915, Hieth 1915), for it is by 

 means of these that the tracheal exuviae of the adult are with- 

 drawn at emergence, but only in some Tanypinse do they 

 assume a condition which might possibly be functional 

 (Thienemann and Zavrel, 1916), and even these are not to be 

 compared with the w^ell-developed spiracles of Oiyhyiephila. 

 Thienemann placed the group as the first subfamily of the 

 Chironomidse, with the Ceratopogoninse second, chiefly on 

 account of the abdominal armature and anal hooks of the 

 pupa; he hoped that a comparison of the larval mouth-parts 

 would confirm this relationship. There is, however, 

 practically nothing in common between the two ; true, the 

 labrum is elongated and flattened laterally as in Ceratopogo- 

 nines, but it has no premandibles, structures which are pro- 

 nounced throughout the Ceratopogoninse (Goetghebuer, 1914) 

 and Chironominse*, audits dorsal, lateral, and ventral sclerites 

 are peculiar to itself. The mandibles and maxillae show 

 no relation to one group more than another, and the narrow 

 u{)turned labium is particularly distinctive. Ceratopogonines 

 have a complicated chitinous hypopharynx within the head, 

 which serves to grind up the food of those terrestrial forms 

 living on solid matter {Forcipomyia^ Atrichopogon) and 

 possibly acts as a pump in those that take liquid food, while 

 other Chironomids have a less involved but constant 

 structure. Orphnephila has no such chitinous structure, 

 but the fleshy hypopharynx and sickle-shaped pharyngeal 

 lamellae point to a relationship with Rhyphidae, Ptycho- 

 pteridae, and, less closely, Culicidae. 



Other characters which set the genus apart are the saddle- 

 like dorsal coverings of the larval body-segments, the 

 antennae, the protuberances of the head, the stout spl t 



* Tunjpinse have o, pustule or fleshy loloe, which Thienemann and 

 Zavrel liuniologi^e with the basal part of the preniaudibles. 



