42 RESEARCHES IN HELMINTHOLOGY AND PARASITOLOGY. 



and brownish ; posterior annulations red or brown. Upper lip so 

 little projecting that mouth appears almost terminal, furnished with 

 short, stiff hairs. Whole number of annulations 50. 



Length 4 lines ; length of setae i-i33d inch to i-8oth inch ; length 

 of podal hooks i -400th inch to i-ijSth inch. 



Habitation. — Found in the .spring of the year in the ferruginous 

 mud at the bottom of springs impregnated with iron, near Phila- 

 delphia. 



2. Chaetogaster, Baer : 



Baer, Nova acta nat. Curios., 1827, p. 614 ; Ehrenberg, Symb. 

 Phys., 1^2)^, Nais diaphijia SindNaisdiastropha. Gruithuisen. Nov. 

 act. nat. cur., 1828, p. 407. 



Body cylindrical, elongate ; mouth inferior, large, triangular ; 

 anus terminal. Podal spines in transverse fasciculi, inferior, simple; 

 the first pair of fasciculi close to the mouth ; the second distant. 

 Intestine straight, capacious. Eyes none. Blood white. Increas- 

 ing by division. Leidy. 



2. Chaelogaster Gu/osus. — Body whitish, translucent ; posteriorly 

 obtuse, ciliated with long hairs ; mouth infero-terminal, large, tri- 

 angular, simple, upper lip digitiform, ciliated. (Esophagus short, 

 narrow; first stomach long, cylindrical, transparent ; second stom- 

 ach large, oblong ; intestine straight, capacious. Podal spines in 

 pairs of fasciculi of 5 or 6 each, simple, divergent, curved back- 

 ward near the free end, retractile ; first pair just posterior to each 

 side of the mouth inferiorly ; second pair removed far back. Usu- 

 ally found in the state of division ; commonly 2 to 4 subdivisions. 



First subdivision i-24th inch, furnished with 6 pairs of fasciculi 

 of podal spines ; the second pair one-half the length of the subdi- 

 vision from the first or oral pair. Second subdivision i-iooth inch; 

 third i-66th inch ; fourth i-iooth inch. Each of these latter fur- 

 nished with 4 fasciculi of podal spines. 



Whole length i line, will contract to half a line ; breadth i-i4oth 

 inch; mouth, when open, i-25oth inch; length of podal spines 

 i-i33d inch. 



Habitation ayid Remarks. — Found abundantly with Hydra fnsca, 

 etc., in the water of marshes in the vicinity of Philadelphia. This 

 worm is very active in its movements and ver}' rapacious. Creep- 

 ing upon bodies in the water, it rapidly elongates the anterior part 

 of its body in various directions, and swallows great numbers of the 

 smaller infusoria. In turn it is much preyed upon by the Hydra 

 fnsca. When the anterior part of the body is elongated in search 

 of food the mouth is much distended and terminal. 



