MOSQUITOES AXD FLEAS. 



27 



of still finer hairs on each of the anal lobes near the base of the anal 

 prolegs, as shown in ng. <>. c. 



On July 6 another lot of eggs was placed in each of the two different 

 vessels. One lot was kept moist and the other dry. and both lots were 

 provided with nothing but the particles of dried blood and a 

 crumbs of dry bread. On July 8 it was discovered that all of the - 

 had hatched. Both vessels had been kept closed under a glass cover. 

 Those between the layers of damp blotting paper had apparently not 

 fed. Some were dead, having crawled up the sides of the vessel. 

 Those in the dry receptable were very lively and had fed abundantly, 

 so that the whole alimentary canal, from one end to the other, was 

 dark brown. 



FlG. 6.— Pulex serraticeps: a. larva: b. head: c, anal end of same— greatly enlarged (original). 



On July 9 the larvae in the dry receptacle had cast the first skin, 

 but upon careful examination were seen to agree perfectly with those 

 of the first stage, except that they were larger. No trace of eyes could 

 be found in either stage. The mandibles apparently bore four blunt 

 teeth. At this date the larvae kept in the moist receptacle had not 

 cast a skin, and appeared almost colorless, having fed very little. In 

 both vessels, however, all the larva' were very active and ran about 

 very briskly. Their movements when crawling recall those of many 

 Tineid larvae. Ten individuals of the second stage were removed to 

 another vessel to see whether they would cast a second skin. 



On July 10 all of the larva' in the original moist vessel died. Those 

 in the dry vessel, which had been fed with bread crumbs, were still 

 growing nicely, and were very active. By July 15 all the larva 1 which 

 had been transferred, to watch for further molts, had died without 



