1850.) 125 



Hydra fusca. When the anterior part of the body is elongated in search of food, 

 the mouth is much distended and terminal. 



3. Rhynchoscolex, n. g. Body cylindical, soft, naked, transversely and finely 

 striated, vibrillated,anteriorly elongated into a proboscidiform appendage. Mouth 

 inferior; anus terminal. Intestine simple, straight. Eyes none. 



3. Rhynchoscolex simplex. Yellowish white, opaque, anteriorly abruptly at- 

 tenuated into a long, cylindrical clavate, proboscidiform appendage : anteriorly 

 abruptly narrowed, obtusely truncate or rounded. Proboscis presenting longitu- 

 dinal and numerous transverse marks. Mouth inferior, at the base of the 

 latter appendage. Intestine straight and capacious. 



Length, 2 to 3 lines ; breadth, l-6th of a line; proboscis l-133d in. long, but 

 may lengthen to l-80th in. 



Habitation and Remarks. A small wriggling worm found among yellowish 

 fragments of vegetable matters and conferva; at the bottom of clear brooks in 

 the vicinity of Philadelphia. Under a very little pressure it undergoes rapid 

 disintegration into globular masses : (cells of the structure distended by endos- 

 mosis ?) 



1. Emea.* Body elongated, plano-convex, soft, proteiform, naked, covered 

 with minute vibrillae. Alimentary canal simple, tortuous, furnished with a giz- 

 zard containing a dental apparatus; mouth and anus terminal. Eyes two or three, 

 on each side of the head. 



1. Emea rubra. Elongated, compressed, contracting irregularly, broadest pos- 

 teriorly, anteriorly obtuse, yellowish flesh colored. Head semi-oval, neck project- 

 ing laterally. Eyes, two or three black spots placed in a line behind one another 

 on each side of the head and neck. Mouth simple, opening into a narrow 

 pharynx; intestine cylindrical, narrowed posteriorly, furnished with a small, 

 round, muscular stomach, containing a corneous dental apparatus at its entrance. 

 Generative apparatus consisting of two very tortuous and capacious tubes, pass- 

 ing the whole length of the body on each side of the alimentary canal. 



Length from 3 to 10 lines; breadth l-5th to l-3d of aline. 



Habitation and Remarks. Found in marshes in the vicinity of Philadelphia, 

 creeping upon dead vegetable substances, or upon the ground. When touched or 

 irritated, it secretes a large quantity of very tenacious mucous. Under slight pres- 

 sure it will voluntarily evert more than one half of the intestinal canal through 

 the mouth, and upon removal of the pressure, after some minutes, will again with- 

 draw it, and apparently without injury having been sustained, as the animal 

 lives for days afterwards in its usual circumstances. The interior of the body, 

 in the intervals of the viscera, is filled with discoidal corpuscles, as in Nais, etc. 

 The interior of the intestine is every where furnished with nutritive villoid ap- 

 pendages. 



2. AwoRTHA.f Body sub-compressed, soft, naked, vibrillated, inarticulate. Ali- 

 mentary canal simple, straight, alternately contracted and dilated. Mouth and 

 anus terminal, simple, indistinct. Eyes none. 



2. Anoktha gracilis. White, opalescent, very contractile, moniliform 



* l/tw, from the disposition the animal has to protrude or vomit forth the ante- 

 rior part of the intestine. 



tarogOow, from the erect position of the animal. 



15 



