664 REPORT UNITED STATES GEOLOGICAL SURVEY. 



lialf of the body appeared to be getting anoulated, whicli was so by the twenty-first day. 

 * * * On tlietweuty-secoud day the annulatious of the anterior half of the body were 

 very distinct, the posterior half was also becoming annulated, and near its extremity I 

 for the first time observed an anal orifice and one to four small epidermal spines. On 

 the twenty- fourth day, the tubular clavate organ before mentioned, occupying the an- 

 terior part of the alimentary canal, was alteruately protruded and retracted as a pro- 

 boscis. The proboscis, when fully protruded, brought into view at its base a second 

 circle of tentacular filaments within the first. On the twenty-sixth day the embryo, 

 when pressed from the egg, progressed forward by moving the posterior half of its 

 body from side to eide, and it alternately protruded and retracted the proboscis and 

 the two circles of tentacular filaments. When all the organs were retracted the head 

 presented a truncate or depressed surface, and in their protrusion the extremities of the 

 outer circle of/ tentaculse and the end of the proboscis first became visible ; as these 

 advanced, the second circle of tentaculai appeared, and when the proboscis was en- 

 tirely protruded, the outer tentaculaj were deeply reflected upon the outside of the 

 body, and the inner circle projected obliquely outward and upward. (See also Leidy's 

 figures and description in the American Entomologist, ii, p. I'JG.) 



It is evidently tbis species whose Labits Dr. Leidy further describes 

 iu his " Flora and Fauna within Living Animals."* I quote as follows 

 from this work : 



The grasshoppers iu the meadows below the city of Philadelphia are very much 

 infested with a species of Gordius probably the same as the former, but in a difterent 

 stage of dcvelopmeut. More than half the grasshoppers in the locality mentioned 

 contain them ; but those in drier places, as in the fields west and north of Philadel- 

 phia, are quite rarely infested, for I have frequently opened large numbers without, 

 finding one worm. 



The number of Gordii in each insect varies from one to five, their length from 3 inches 

 to a foot; they occupy a position in the visceral cavity, where they lie coiled among 

 the viscera, and often extend from the end of the abdomen forward through the thorax 

 even into the head. Their bulk and weight are frequently greater than all the soft 

 parts, including the muscles, of their living habitation. Nevertheless, with this rela- 

 tively immeuse mass of parasites, the insects jump about almost as freely as those not 

 infested. 



The worms are milk-white in color, and undivided at the extremities. The females 

 are distended with ova, but I have never observed them extended. 



When the bodies of grasshoppers, containing these entozoa, are broken and laid upon 

 moist earth, the worms gradually creep out and pass below its surface. Somespeci- 

 meus which crawled out of the bodies of grasshoppers and penetrated into earth con- 

 tained iu a bowl, last August, have undergone no change, and are alive at the present 

 time (November, 1852). 



In the natural condition, when the grasshoppers die, the worms creep from the body 

 and enter the earth, for, suspecting tlie fact, I spent an hour lookiug over a meadow 

 for dead grasshojipers, and, having discovered five, beneath two of them, several 

 inches below the surface, I found the Gordii which had escaped from the corpse. 



Some of the worms put in water lived for about four weeks, and then died from the 

 growth of Addya jirolifera. What is their cyclical development ? 



The history of the Gordius aquaticus has been mostly cleared up bj' A. 

 Villot,t and the following account is condensed from his memoirs: 



Tbe eggs (Plate LXIII, Fig. 7, a) are laid iu long chains; they are white, 

 and excessively numerous. The yolk undergoes total segmentation. 

 (Plate LXIII, Fig. 7, b.) At the close of this period, when the yolk is sur- 

 rounded by a layer of cells, the germ elongates at what is destined to 

 be the headend, this layer pushes in, forming a cavity, and in this state 

 itiscalleda "gastrula."' (PlateLXIII,Fig.7,c.) Bythistimetheembryo 

 becomes pear-shaped (Fig. 7, d); then it elongates. Subsequently the 

 internal organs of digestion are formed, together with three sets of stiff", 

 spine-like appendages to the head, while the body is divided by cross-lines 

 into segments. The head lies retracted within the body. (Fig. 7, e.) 



In hatching, it pierces the egg membrane by the aid of its cephalic 

 armature, and escapes into the water, where it passes the early part of 



* Smithsonian Contributions to Knowledge, v. 1853. 



tMunographie des Dragonneaux (Genre Gordius Dujardin), ])ar A. Villot. (Archives 

 de Zuologic expcrimeutale et geu6rale, tome 3, No. 1, 2, 1874, Paris.) 



