1893.] OO [Packard. 



and TipulidfB, were the earliest and most generalized types, while the 

 Muscidse, with their apodous maggots present the extreme of modification 

 though not of specialization, and so with other apodous insects and apo- 

 dous Arthropoda in general. 



To return to the Cochliopodidae : the great difference between the tuber- 

 culated and spinose and the smooth, unarmed genera show that the forms 

 were more or less plastic, and though all of them are born without abdom- 

 inal legs, yet after atrophy had taken place, the larvae of different genera 

 became exposed to quite different surroundings and stimuli, and responded 

 to such varied changes with t)»e result seen in the numerous genera char- 

 acterizing the eastern regions of North and South America, as well as 

 Southeastern Asia; Europe only possessing two species, and none being 

 yet known from the Pacific slope of North and South America. 



It will, of course, be a matter of great interest to examine the embryos 

 of this family in order to determine how late in embryonic life the abdom- 

 inal legs disappear, for, undoubtedly, as in the embryos of such Lepidop- 

 terous larvae as have been examined by embryologists, each segment bears 

 a pair of temporary embryonic legs. Probably the legs are represented 

 by the transversely oval ventral areas or muscular folds on each segment 

 of the abdominal region in the slug-worms. 



As a result of studies with larvae and moths I may add that the genus 

 Heterogenea is more largely represented in the United States tlian for- 

 merly supposed, and the genera Kronea and Torlricidia are with liiile 

 doubt synonyms of Heterogenea, the characters which I originally em- 

 ployed not being of generic value. 



The Life History of Empretia stimulea Clemens. 



I am indebted to Miss Emily L. Morton, of East Windsor, N. Y., for 

 the eggs of this interesting form. The larvae hatched July 9 to 13 at 

 Brunswick, Me., from the eggs sent a few days previous. 



Egg. — As usual in the family, an irregular, oval, flattened, scale-like 

 body, with a very thin edge ; under a half-inch objective the shell is seen 

 to be thin, transparent, and without any markings. They are laid in an 

 irregular mass, partly overlapping each other. Length, 1^ to 3 mm. ; 

 breadth, 1 mm. 



Freshly Hatched Larva. — Length, 1.3 mm. The body is broad and high, 

 about three times as long as high, but much more cylindrical than in the 

 full-grown larva. The head is pale and the body is pale straw-yellow. 

 The eyes are black and distinct. The prolhoracic segment is large, some- 

 what hood like, not bearing any visible tubercles, but with two obsolete 

 warts, giving rise each to three hairs. The other segments are in this stage 

 distinctly marked, especially dorsally and ventrally. On each of the 

 second and third thoracic, and the first abdominal segments is a pair of 

 high conical tubercles, which are moderately thick at base, and nearly as 

 long as one-half the thickness of the body, each giving rise to but three 



