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TRANS. ST. LOUIS ACAD. SCIENCE. 



consist of two or three lines, without measurements; and, for aught the 

 student can see to the contrary, several of them apply to one and the same 

 species. A name, a slight modification of the descriptive language, with- 

 out altering the description, and behold a new species ! Such is the im- 

 pression which Macquart's work, more especially, in this genus, leaves on 

 the mind. The Muscidre are proverbially difficult to study on account of 

 the many close resemblances which the different species present. In such 

 difficult genera as Sarcophaga science is best served by full descriptions 

 of the different stages, coupled, if possible, with the habits of the species; 

 and my own object is to so characterize the present species that future stu- 

 dents cannot fail to recognize it— the name under which it goes being of 

 minor importance. 



The larva differs from Packard's description of that of carnaria in the 

 character of the prothoracic spiracle, in lacking the 12 blunt spines 

 around the anal spiracular region, and in having the clear space in the 

 peritreme of the anal spiracles, by which it seems to agree more with his 

 description of Calliphora, and to indicate that this feature cannot be 

 looked upon as of generic value, as Dr. Packard suggests it may be.* 



Descriptions of tzvo new Jlfot/is. 



By Chas. V. Riley. 



Genus Xilllthoptera Guenee. 



Xanthoptera Ridingsii, n. sp. (Fig. 12 d")- — Colors pale, bright, 

 glossy straw-yellow and brown-black. Primaries yellow with a dark band 

 across the base, reaching close to the thorax on the costal half, only \ as 

 wide and outwardly obliquing on the inner half; a second band across the 

 middle as wide as the costal part of the basal one, slightly arching with the 

 posterior border; a third much broader occupying the posterior third of 

 wing, with a narrow line more or less distinctly separated from its arched 



* On the Transformation of the common House-fly, with Notes on allied Forms, by 

 A. S. Packard, Jr., M.D. The author of this interesting essay, which received the Walker 

 prize and appears in the Proc. Bost. Soc. Nat. Hist., vol. xvi. 1S74. does not seem to have 

 been familiar with Samuelson's little work on The Earth-vjorm and the Housefly, or with 

 some others cited in Hagen's Bibllotheca, as he refers to only three authois (DeGeer, Bou- 

 che, and Keller) who have treated of the habits of Musca domestica. His own paper is, how. 

 ever, replete with original observations, and from a comparison of the larvae of Musca, Cal- 

 liphora. and Sarcophaga, he mentions the number of principal divisions of the prothoracic 

 spiracle, and the absence or presence of the clear space in the peritreme of the anal stigmata 

 as of generic value. Thus in Musca the main divisions in the prothoracic spiracle are said 

 to number 6-S, in Calliphora 9 and in Sarcophaga 11 ; while, aside from these differen- 

 ces, the only other structural difference between the last two genera is said to be in the 

 absence of the clear space in the peritreme of the anal stigmata in Sarcophaga and its 

 occurrence in Calliphora. My own studies of Sarcophaga sarracenice would seem to les. 

 sen the importance of these characters as generic guides. 



