108 MISCELLANEOUS PAPERS. 



ovipositioii — and it has been seen that one is often baffled for a con- 

 siderable time in effecting this — the females can be opened and the 

 uterine eggs obtained. Those eggs contained in the upper extent of 

 the uterus are of course the most recently fertilized and the least 

 developed of the uterine eggs. If they have a very thin shell it is 

 probable that they hatch within the uterus, and that the female there- 

 fore deposits living maggots. Such is the case with Dexodes nigripes^ 

 Compsilura eoncinnafa, and Eupeleteria magnicornis^ and with such 

 dexiine and macronychiid flies as we have studied; and from the char- 

 acter of the eggs such is possibly the case with Zygobothria gilva 

 and Z. nidieola, though only ovarian eggs of the last have as yet been 

 secured. Furthermore, if the hatched uterine maggot is furnished 

 w^ith a membranous encasement of its anal end, it shows that this 

 maggot is not to be deposited on the caterpillars, but is to be at- 

 tached to the stems or leaves. Such is the case with magnicornis. 

 The uterine maggots of nigi'ipes and concinnata have no such anal 

 membrane of attachment, and are introduced into the caterpillars. 

 If the uterine eggs are slender and very elongate it is quite cer- 

 tain that they hatch in the uterus. Such is the case with the dexiine 

 and macronychiid flies. 



If, however, a thin-shelled egg is furnished w^th a pedicel, this is 

 proof positive that the Qg,g is intended to be deposited as such, but 

 the thin shell indicates that it is normally deposited at an advanced 

 stage of development of the embryo. Such is the case with Parexo- 

 rhta elielonia^ ^ whose eggs have a pedicel, and should normally hatch 

 soon after deposition. The few occurrences of hatched maggots in 

 the uterus of chclonkv were doubtless due to an abnormal hatching 

 of the eggs after the death of the females. No doubt, however, 

 cheloniw is in process of transition from an ovipositing to a larvipos- 

 iting habit. It is greatly to thi* advantage of the species that the egg 

 should hatch shortly after deposition, for this guards against its loss 

 by molting. We have found that a large percentage of the eggs are 

 molted oli' hy the caterpillars. Those sj^ecies which deposit living 

 maggots derive a still greater advantage in this direction. Those 

 eggs which have a thick shell are intended to withstand atmospheric 

 conditions for some time, and may be deposited a week or more before 

 the embryo is fully developed. Such is the case with Parasetigena 

 scgregata., 11 emimasicera sp. ( ?), Tricholyga grandis, Tachina larva- 

 rum^ T. iftilis, T. clisiocampce^ and the Japanese Tachinas. That the 

 eggs of these are large shows that they are to be deposited on the 

 caterpillars. 



Again, if the eggs are minute it is quite certain that when matured 

 they will be black and highly chitinized, and each character points 

 directly to a habit of leaf-oviposition. The chitinization indicates 

 that the eggs are intended to withstand exposure to the elements and 



