ENTOZOA. 97 



The next human entozoon of the Nematoid order belongs to the 

 genus Trichocephalus, which, like Filaria, is characterised by an orbi- 

 cular mouth, but differs from it in the capillary tenuity of the anterior 

 part of the body, and in the form of the sheath or preputial covering 

 of the male spiculum. The species in question, the Trichocephalus 

 disparRud. (Jig. 43.) is of small size, and the male is rather less than 

 ^ — >v^ 43 the female. It occurs most commonly in the csecum 



%£/ ^"-^S^ and colon, more rarely in the small intestines. Occa- 

 " sionally it is found loose in the abdominal cavity, 



Trichocephalus , p,. . rn 



dispar. Nat. size, havmg perforated the coats of the intestine. The 

 capillary portion of this species makes about two-thirds of its entire 

 length ; it is transversely striated, and contains a straight intestinal 

 canal ; the head («) is acute, with a small simple terminal mouth. 

 The thick part of the body is spirally convoluted on the same plane, 

 and exhibits more plainly the dilated intestine ; it terminates in an 

 obtuse anal extremity, from the inner side of which project the 

 intromittent spiculum and its sheath. 



The species called Spiroptera Hominis was founded by Rudolphi 

 on some small nematoid worms expelled, with many larger elongated 

 bodies of a solid texture, and with granular corpuscles, from the 

 urinary bladder of a woman, whose case has been described by Mr. 

 Lawrence in the Medico-chirurgical Transactions.* The Spiroptera 

 varies from eight to ten lines in length ; the head is truncate, the 

 mouth orbicular, with one or two papilla, the body is attenuated at 

 both extremities ; the tail in the female, thicker, and with a short 

 obtuse apex ; that of the male more slender, and emitting a small 

 tubulus ; a dermal aliform production near the same extremity 

 determined the worms in question to belong to the genus Spiro- 

 ptera. I 



The most formidable, but, happily, the rarest of the nematoid 

 parasites of man, the Strongylus gigas, also infests the urinary 

 system, but is developed in the kidney, where it hns attained the 

 length of three feet, with a diameter of half an inch ; occasioning sup- 

 puration and destructive absorption of that important glandular organ. 



The male ijig' 44.) of this species is less than the female, and is 

 slightly attenuated at both extremities. The head («) is obtuse, the 

 mouth orbicular, and surrounded by six hemispherical papillae ; the 

 body is slightly marked with circular striae, and with two longi- 

 tudinal impressions ; the tail is incurved in the male, and terminated 

 by a dilated pouch or bursa, from the base of which the single intro- 

 mittent spiculum {g) projects. In the female the caudal extremity 



* Vol. ii. p. 385. t XL VII. r- 251. 



