J 24, [Dec. 



Description of new genera of Vermes. 

 By Joseph Letdy, M. D. 



1. Peloscolex. n.g. Setae in two rows, 6 to 10 in each fasciculus; podal 

 hooks in two rows, in twos or threes, bifurcated at the free extremity; each an- 

 nulation furnished with a circle of prominent tubercles, with numerous smaller 

 ones. Upper lip hardly projecting. Girdle not prominent. Blood red. 



1. Peloscolex Variegatus. Body cylindrical, posteriorly obtuse, anteriorly 

 sub-acute. Setcc simple, usually 10 in each fasciculus anterior to the girdle, 

 absent in the posterior 22 annulations. Podal hooks anteriorly in threes, diver- 

 gent, strong, sigmoid, bifurcated at the extremity ; posteriorly in twos, one rudi- 

 mentary. Each annulation furnished with a circlet of elevated, rounded tubercles, 

 1. sooth in. in heighth, and numerous smaller ones, also arranged in transverse 

 circles. Anterior, 3 or 4 annulations reddish ; after these 25 are deep black, 

 except the tenth or girdle, which is broad and brownish ; posterior annulations 

 red or brown. Upper lip so little projecting that the mouth appears almost termi- 

 nal, furnished with short, stiff hairs. Whole number of annulations 50. 



Length 4 lines ; length of setae, l-133d in. to l-80th in. ; length of podal hooks 

 l-400th in. to l-178th in. 



Habitation. Foand in the spring of the year in the ferruginous mud at the 

 bottom of springs impregnated with iron, near Philadelphia. 



2. Chaetogaster, Baer: 



Baer, Nova acta nat. Curios. 1827,;?. 614; Ehrenberg, Symb. Phys., 1831. 

 Nais dia'phina and Nais diastropha, Gruithuisen. Nov. act. nat. cur. 182S, 



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. Increasing by division. Leidy. 



2. Chaetogaster GULOsus. Body whitish, translucent; posteriorly obtuse, cili- 

 ated with long hairs; mouth infero-terminal, large, triangular, simple; upper lipdi- 

 gitiform, ciliated. (Esophagus short, narrow ; first stomach long, cylindrical, 

 transparent ; 2nd stomach large, oblong ; intestine straight, capacious. Podal 

 spines in pairs of fasciculi of 5 or 6 each, simple, divergent, curved backward 

 near the free end, retractile ; first pair just posterior to each side of the mouth 

 inferiorly ; second pair removed far back. Usually found in the state of di- 

 vision ; commonly 2 to 4 subdivisions. 



First subdivision l-24th in. ; furnished with 6 pairs of fasciculi of podal spines, 

 the second pair one half of the length of the subdivision from the first or oral 

 pair. Second subdivision 1-lOOth in. ; third, l-66th in. ; fourth 1-lOOth in. 

 Each of these latter furnished with 4 fasciculi of podal spines. 



Whole length, 1 line ; will contract to half a line ; breadth, l-140th in. ; 

 mouth, when open, l-250th in. ; length of podal spines, l-133d in. 



Habitation and Remarks. Foundi abundantly with Hydra fusca, etc., in the 

 water of marshes in the vicinity of Philadelphia. This worm is very active in 

 its movements and very rapacious. Creeping 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 



