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VII. Illustrations of the 6th $ ventral segment in 17 Osmia- 

 species of the adunca- Group, witU a Note on the 

 synonymy of four species, and descriptions of four 

 which seem new. By the Rev. Francis David 

 Morice, M.A., F.E.S. 



[Read December 5tli, 1900.] 



Plates VII and VIII. 



Having dissected numerous $ $ of Osmia, Pz., representing 

 among them, I believe, 17 palsearctic species of the adunca- 

 Group, I find that in all of them the hidden 6th ventral 

 segment of the abdomen has a very elaborate and singular 

 structure (reminding me a good deal of the 7th ventral in 

 Golletes) — evidently highly specialised for some important 

 (probably sexual ?) function. 



In each, the segment in question emits from its apex a 

 distinct and conspicuous membranous appendage of some 

 paradoxical form, which form differs so much in the various 

 species that many can be distinguished by it at a glance. 



How far this structure is peculiar to or universal in the 

 adunca-Grou]), I cannot yet say. But so far I have only 

 found it there, and in one little " maniple " of species (one 

 of which may be crenulata, Mor., and the others un- 

 described) which, according to present ideas, would be 

 grouped, but as I suspect not rightly, with papaveris. 

 Neither papaveris itself nor its allies, cristata, saundersi, 

 bisulca, etc., have any such appendage to the 6th ventral, 

 and the character seems to me, fully as important as the 

 form of the 7th dorsal, on which the groups of papaveris 

 and adunca are at present separated. 



Unfortunately the segment cannot be viewed, without 

 dissection of the specimen. But when extracted, its 

 beautiful forms and most interesting structure amply repay 

 the trouble of bringing it to light; and the characters 

 presented by it in the various species are so clear and 

 constant, that I think they well deserve an attention which 

 has not yet been paid to them by the framers of specific 

 diagnoses. In no Group of the Genus, perhaps, have 

 describers been less successful in so characterizing their 



TRANS. ENT. SOC. LOND. 1901. — PART II. (JULY) 



