ASCARIS LUMBRICOIDES. 223 



Spec. Char. Body naked ; with a small groove or 

 longitudinal depression on each side ; tail ohtuse. 



A. liunbricoides, Syst. Nat. Gmelin. p. 3029. Hoop. Mem. Med. Soc. v. p. 233. 



Rudolph. Entoz. p. 37, 267. Wern. Verm. Intesl. p. 75. t. 7. i'. 153, 159. 

 Lombricdes Intestines, Fr.; Verme Rondo Cambrico,lt.; Lombrig. Sp. ; Rvnd- 



icurm, Ger. j Menncskeorm, Dan. ; Metiisco.mask y S\te<l. 



The Lumbricus Teres, or Round Worm, is about the thickness 

 of a goose-quill, and from twelve to fifteen inches long. It is gene- 

 rally of a brownish-red colour ; but it varies considerably according 

 to the nature of the aliment with which the animal is filled. When 

 recently passed they are quite transparent, and the viscera and organs 

 of generation may be seen through the integuments ; but on ex- 

 posure to the air, they soon assume a light and opaque yellow 

 tinge. The head is distinguished from the rest of the body by a 

 circular depression, and it is furnished with three tubercles or 

 valves found in no other entozoa. In the centre of these tubercles 

 is a small tube, which is the opening of the mouth. The body is 

 cylindrical, tapering towards the two extremities, with a small 

 groove or depression extending on either side, from the head to the 

 tail. The animal has external integuments, muscles, digestive and 

 genital organs, and according to some authors, even a circulating 

 and nervous system.* The integuments consist of two distinct 

 membranes, the cuticle which is thin, smooth, and transparent, 

 and the cutis vera or true skin, which is somewhat thicker than the 

 former, very strong, elastic, and transparent. The muscles lie 

 throughout under the skin, and have longitudinal and transverse 

 fibres. The digestive canal is straight, extending the whole length 

 of the worm, and terminating by a transverse fissure in the anus, 

 near the extremity of the tail ; each sex is in a different individual. 

 The male is smaller than the female, and is distinguished from the 

 latter by having the end of the tail bent. The organs of generation 

 are situated near the anus, and in the female fill a great part of the 

 animal. It resembles in its general aspect the common earth- 

 worm, but is readily distinguished from it by the want of setae or 



* See Anatomie des vers Zntestinaux, par Jules Cloquer, Paris, 1821. 



