20 STRUCTURE OF CERTAIN DIPTEROUS LARV^. 



Chrysomyia ( ?) 

 (Plate III, figs. 39, 47, 52.) 



Head showing a lobe each side, eacli tipped bya distinct antenna; 

 mandibles two, well separated; base of second segment a swollen 

 ring, finely obliquely striated ; each of the folio wmg segments with a 

 basal swollen ring, and furnished with spinules; beginning with the 

 fifth segment there is an apical, fusiform, spinulose area each side, 

 pressing against the ring of the next segment; elsewhere the sur- 

 face is smooth and shining, each segment with two faint grooves 

 around its middle; anterior spiracle with about 10 lobes. The last 

 segment shows below at base a transverse spinulose area; the anal 

 area is not very prominent, spinulose, and with a prominent conical 

 tubercle at each outer corner; the posterior stigmal area occupies 

 the . dorso-caudal surface, but hardly forms a pit, with six small 

 tubercles on each lip, those on upper lip rather larger; the stigmal 

 plates are rather close together, have no button, and each shows 

 three straight slits, subparallel to those in the other plates. 



Various specimens taken from fish, at the Barbados, West Indies. 



CALLIPHORIN^. 



In the Calliphorinse there are two hooks or mandibles, and the 

 posterior stigmal plates have each three straight slits directed more 

 or less toward those of the opposite plate. The stigmal field is 

 usually outlined by conical tubercles, but not especially depressed. 

 The anal tubercles are usually spinose, and the prothoracic spiracles 

 rarely, if ever, have more than 15 lobes. The segments usually 

 show a more or less complete ring or spinose area on the segments 

 beyond the fifth. This group is very close-to the Sarcophagidre, and 

 some species of Lucilia are nearly as well placed there as here. 



Calliphora erythrocephala Meig. 

 (Plate III, figs. 62, 63.) 



Head distinctly bilobed from above, each lobe with a minute 

 papilla; two well-separated mandibles; anterior spiracles with from 

 nine to twelve lobes. Beginning with the third, each segment shows 

 an apical swollen ring or girdle, whose surface is scabrous; these rings 

 are broader below than above, and are here emarginate on the poster- 

 ior middle. Each ventral segment, beginning with the fifth, is 

 divided by a transverse groove near the middle. The anal area shows 

 a smooth median process, divided in middle, and at each outer corner 

 is a cone. The stigmal field is rather concave, the upper lip with three 

 small tubercles each side, the lower lip with two larger tubercles 

 each side, and a median pair smaller and lower down; the stigmal 



