230 [November, 



" Eeitrage," pp. 230 — 232) ; (5) another point in which O. raphani 

 agrees with other parthenogenetically reproductive arthropods is its 

 many-broodeclness in a season. There may be three or four generations 

 in direct succession in the year, and there is a constant succession of 

 eggs all the time. In this it appears to differ from any of its allies 

 with which I am acquainted. (6) Finally, the case of G. rapliani 

 would seem to be one of true parthenogenesis in its most restricted 

 sense — the same beetle which in the unimpregnated state lays sterile 

 eggs, with here and there one capable of development, after receiving 

 the male element, laying eggs which are fertile and develop in the 

 ordinary way. That is to say, the ova are true ova, and not pseud-ova 

 or buds, the parent a perfect female and not an "Amme" like the 

 summer Aphis. 



Milford, Letterkenny, Ireland : 



September 22nd, 1880. 



DE. F. MULLER'S DISCOVERY OF A CASE OF FEMALE DIMORPHISM 

 AMONG DIPTERA. 



BY BARON C. E. OSTEN-SACKEN. 



"We owe to Dr. Fritz Miiller, in Brazil, the important discovery! 

 of the hitherto unknown larva? of the Blepharoceridce, a very aberrant J 

 Family of Diptera Nemocera, of which a dozen species are at present 

 known, remarkable for their sporadic distribution nearly all over the 

 world (Europe, Ceylon, North and South America). In connection 

 with this discovery of the larva?, Dr. Miiller publishes another very 

 interesting and novel fact, the existence, in the species observed by 

 him (which he names Paltostoma torrentium), of two sets of females, 

 the one of which has the organs of the mouth built upon the plan of 

 the trophi of blood-sucking Diptera, while in the other, as well as in 

 the male, the mandibles are wanting. These females differ from each 

 other besides, in the size of the eyes (separated in both cases, while 

 they are contiguous in the male), and in the structure of the last 

 tarsal joint. For details I refer to Dr. Miiller's circumstantial and 

 conscientious article in the October Number of the German periodica 1 

 " Kosmos," and will only add, that these flies were obtained by Dr 

 Miiller in large numbers by cutting open nearly ripe pupa?, but, as it 

 seems, were never found in the open air. 



As I have paid some attention to the Family of Blepharocerida. 

 and am the only person who knows de visu all the described species 

 (always rare in collections), I feel bound to make the following re 

 marks, which suggested themselves to me in reading the above-quoted 1 

 article. 



