2 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.60. 



preparation of the remainder of the plates, the drawing of descrip- 

 tions, the construction of the synopsis, and arrangement of the ilhis- 

 trations, as well as the synonymy, arc the work of the author, ex- 

 cept as may be specifically indicated hereafter. Only those puparia 

 from which the adult fly issued and was authoritatively determined 

 have been used as a basis for this work, and such specimens have 

 been preserved for future reference in the United States National 

 Museum. 



This paper is based on the puparia of one hundred species of 

 Muscoidean flies, of which 99 have been figured, two species being 

 so closely similar as not to be separable by this means. The puparia 

 of a considerably greater number were examined in order to test 

 the characters upon which the present work is based, and, with a 

 single exception, the determination of the species of the puparium 

 in hand was easily accomplished by means of the following synopsis. 

 The exception referred to is that of Frontina aletiae, which it has 

 been found impossible to separate from that of Frontina archip- 

 pivora. Apparently these species are very closely allied. 



The principal characters used are as follows : 



Stigmal plate. (PI. 1, fig. 1.) — The posterior stigmata are heavily 

 chitinized and divided into two distinct areas, each area being called 

 a stigmal plate. Each plate has two or more openings for respira- 

 tion, and these openings are called slits., which connect with the main 

 tracheae. 



Slits. (PL 1, fig. 3.) — Various terms are used herein to designate 

 the different types or styles of slits, as follows : 



Serpentine. (PI. 4, figs. 15-17.) — This term means a long winding 

 slit somewhat resembling a snake or serpent. It may have few or 

 many curves. 



Brain coral. (PI. 3, fig, 12.) — This term means that the slits are 

 so formed that the surface of the stigmal plate has a great resem- 

 blance to brain coral {M eandrina., various species). 



Ph,in slits. (PL 1, fig. 1.)— These vary from straight to slightly 

 curved or angulated. 



Button. (PL 1, fig. 2.) — This character varies in shape from 

 round to nearly square and may be slightly raised or depressed. Its 

 position varies a little, but it is always to be found on the inner half 

 of the stigmal plate, or that half nearest the vertical axis. The 

 button, according to Dr. J. C. H. De Meijere,^ is the vestigial re- 

 mains or scar of the posterior stigmata of the first stage larva. 

 The stigmal plate afterwards forms around this scar and becomes 

 heavily chitinized in the last stage of the larva. 



Ridges. (PL 1, fig. 3.) — Elevations on the dorsum of the stigmal 

 plate and upon each ridge is located a slit. The ridge is always 



"Tijdschr. v. Entom., vol. 38, 1894, pp. 6.5-100. 



