1S(J2.] 151 



— for the 8ycani(ire usually stands along the margins of streams — must be 

 drowned after abandoning their mines. 



Characters of the larvae of MYCETOPHILID^ffi. 



BY BARON R. OSTEN SACKEN. 



(Plate 2.) 



A considerable amount of information on the earlier stages of existence 

 of Diptera is scattered through the entomological publications. Only a few 

 years ago, Mr. Haliday prepared a list of nearly all the references on this 

 subject. (^List of the genera and species of the British Diptera^ the 

 earlier stages of which are more or less perfectly known, with references 

 to the principal authorities^ in the Natural History Review, p. 180.) The 

 next step, after a publication of this kind, is to digest the materials thus 

 collected, and to reduce to a more compact form the information contained 

 in them. But this being done, one becomes very soon aware that the in- 

 crease of knowledge thus obtained is rather insignificant, that a vast num- 

 ber of references add but very little to the facts, and that a real advance 

 can be obtained only by fresh investigation. The knowledge of larval 

 forms, due to former observers, does not, in most cases, supply us the 

 knowledge of the characters of these forms. The desideratum of dip- 

 terology in its present state is to establish the natural character of each 

 family in its larval form, as well as the natural character of at least the 

 principal genera within each family, during the same stage of existence. 



An attempt pf this kind on the family of Mycetophilidae, is offered in 

 this paper. It contains : Ist.-A comparative description of the exter- 

 nal anatomy of the principal genera in their larval form. 2d.— A brief 

 account of what is known about the habits of each genus. 3d.— A list of 

 references, with a short notice on the importance of each. 



It will be observed that the description of the transformations of Myceto- 

 hia pallipes, usually considered as belonging to the Mt/cetophilidsej has 

 been omitted. The earlier stages of this insect, as observed and described 

 in perfect agreement by Lyonnet, Dufour and Guerin, are totally at vari- 

 ance with those of the other genera of the family, the larva being amphi- 

 pneustic, and the pupa having spines round the abdominal segments, like 

 those of the Tipulidx. Both resemble most strikingly the larva and pupa 

 Rhyplius. I have deemed it better, therefore, to exclude this genus from 

 the family until further research indicates its true location. 



The principal descriptions of the larvae of Mycetophilidae have been 

 given by Dufour, Bouch6 and Heeger. 



