RESEARCHES IN HELMINTHOI.OCxY AND PARASITOLOGY. 247 



continued for a week after the unusual mode of administering their 

 food was stopped. 



At the end of two weeks from the commencement of feeding the 

 frogs I killed one of them, and carefully examined the intestinal 

 canal and other organs for the NcniatoideuDi, Passali, but not a trace 

 of it was to be found. The cloaca yet contained one or two frag- 

 ments of the skeleton of the Passa/us, with some epithelial scales, 

 mucus, and a dark, mud-like, granular matter, but nothing else. 

 The entozoon had been digested with the soft parts of the insect. 

 Two days after I killed the remaining frogs, but in none did I dis- 

 cover the slightest trace of the entozoon in question. From the re- 

 sults thus obtained we may conclude that this parasite finds no con- 

 dition favorable to its existence, leaving out of the question entirely 

 any farther development, in frogs, or probably in any reptile. But 

 still the entozoon may pass part of its existence in other animals. 

 In a state of nature frogs would rarely have a chance of feasting 

 upon Passa//(s (the habitation of Passa//(s, however, offers no reason 

 why a frog should not occasionally feast upon them. At one time 

 I thought the insect was confined to the haunts in which it is usually 

 found, but it undoubtedly flies at night, as I have found it in places 

 where some da3'S before the}- did not exist, and my late friend, Dr. 

 Benj. Kern, once brought me half a pint of this insect, which he 

 obtained on the Atlantic ocean a few miles from shore, with numer- 

 ous other insects, one morning after there had been a brisk wind in 

 the night), because the latter is found in forests, beneath bark and 

 in the wood of decaying dead trees, and here the woodpecker {Picus) , 

 or other insectivorous birds, would be most likely to meet with it, 

 and with such birds a similar experiment to the one performed with 

 frogs might be tried to see if the development of the entozoon would 

 not advance within them. 



2. Neviatoideniu thoracis cavitatis Passali cornuti (pi. 1 1 , Fig. 46) . — 

 This is an anguillula-like worm in an imperfect condition, found 

 occasionally in the cavity of the thorax of Passalus cortiidiis. It 

 resembles an embryonic Ascaris. Its movements are active and 

 wrigghng. It is whitish, translucent, cylindrical, and attenuated 

 and acute posteriorly. 



Structure. — Integument transparent and colorless. CEsophagus 

 long, narrow, cylindrical, and faintly outlined. Intestine broad, 

 cylindrical, granular in appearance, and faintly outlined. Anus an 

 oblique fissure, not very distinct, just in advance of the tail, which 

 latter is short and acute. Length i-66th inch ; breadth i-ioooth 

 inch. 



