Dr. O'Bryen Bellingliam on Irish Entozoa. 477 



,^ _, . , f Small intestine of homed owl (Otus vul- 



10. Tnchosoma | ^^^.^y 



1 1 . .... _ Small intestine of jjigeon ( Co/Mmia Livia). 



r Ceeca and rectum of jackdaw {Corvus 



^- 1 Monedula). 



13. * Intestines of hake {Merlucchis vulgaris). 



Genus 3. Trichocephalus, 

 (Derived from dpi^, capillus, and KefaXi), caput.) 

 Body cylindrical and elastic, anterior portion capillary and suddenly 

 passing into the thicker or posterior part (by this it is distin- 

 guished from the genus Trichosoma, in which the increase is very 

 gradual); mouth orbicular ; j^ra/^ simple, contained in a sheath. 

 The name Trichocephahs was given to this genvis by Goetze, 

 and adopted by Ruclolphi. It was formerly named Trichurus 

 (from 6p\^, capillus, and ovpa, cauda), from the erroneous suppo- 

 sition that the capillary portion was the tail. The species inhabit 

 the large intestines, particularly the csecum of the mammalia ; 

 they do not occur in either birds or fish. The genus is not nu- 

 merous in species. Rudolphi has arranged them in two subdi- 

 visions; our native species belong only to one of these subdi- 

 visions. 

 1. Trichocephalus dispar[ .... Large intestines of man (Homo). 



* The genus Trichosoma is very rare in fish ; Rudolphi or Bremser 

 has never found them ; the only species which has been as yet de- 

 scribed to occur in these animals, is one noticed by Creplin in his 

 ' Observationes de Entozois.' This species I found in the intestines 

 of the hake (Merhiccius vulgaris) ; the longest specimen is upwards 

 of an inch in length, the body slender, colour perfectly white. As 

 there cannot be a doubt that it is a new species, I would venture to 

 suggest the name Trichosoma gracilis for it. 



t The Trichocephalus c/ispar has been longer known than any other 

 species of the genus ; and although stated by several writers to be 

 rare in these countries, in the course of mj^ experience I have found 

 it by far the most common species inhabiting the alimentary canal of 

 the human subject. I have examined the intestinal canal of ninety 

 individuals, who died in St. Vincent's Hospital, Dublin, of various 

 diseases, and whose ages varied from three years to seventy ; and in 

 eighty-one out of the ninety, I found a larger or smaller num- 

 ber of this species ; sometimes only one or two existed, sometimes 

 they were in considerable abundance ; the largest number I have met 

 with in the same individual was 119 ; sometimes they were attached 

 to the mucous membrane, more commonly they M'ere free ; they al- 

 most always inhabited the large intestine, particularly the caecum ; 

 I have, however, met with them in the small intestine. The male 

 appears to be as common, or perhaps more common than the female, 

 which is contrary to what happens in most other genera of Nema- 

 toidea. 



