INDIGENOUS TO IRELAND. 349 



7. Trichosoma D Urinary bladder of rat. 



8. „ Small intestine of rat. 



9. „, Stomach of hedge-hog. 



10. „ Small intestine of horned owl. 



11. „ Small intestine of pigeon. 



12. „ Ccem and rec<wm of jackdaw. 



13. „ E Intestines of hake. 



Genus 3. — Trichocephalus. 



(Derived from t^'I, capillus^ and «£^aA>l, caput. 



Body cylindrical and elastic, anterior portion capillary and suddenly pass- 

 ing into the thicker or posterior part (by this it is distinguished from 

 the genus Trichosoma, in which the increase is very gradual) ; mouth 

 orbicular ; penis simple, contained in a sheath. 



The name Trichocephalus was given to this genus by 

 Goetze, and adopted by Rudolphi. It was formerly named 

 Trichufis (from r^ik, capillus, and ov^a, cauda), from the 

 erroneous supposition that the capillary portion was the tail. 

 The species inhabit the large intestines, particularly the ccc- 

 cum of the Mammalia ; they do not occur in either birds or 



D. This species of Trichosoma I have very frequently found in the urin- 

 ary bladder of the common Norway rat ; in some cases only one or two 

 occurred, in others, six, eight, or upwards. Many were free in the blad- 

 der ; others so firmly attached by their anterior extremity to the mucous 

 membrane, that they broke across when pulled ; and some even remained 

 adherent, after having been placed in spirits of wine. They are the largest 

 species of Trichosoma which I have seen, the posterior division of the 

 body in some being so thick as in a certain degree to resemble this part in 

 the Trichocephalus, from which, however, they are readily distinguished, 

 the increase in diameter being gradual, and not sudden. They are about 

 8 lines in length, the body white and cylindrical, the posterior extremity 

 rounded ; in the thicker part of the body, the alimentary canal appears to 

 be somewhat spiral, and is surrounded by the convoluted ovaries. All the 

 specimens which I have appear to be females. 



This species has not, I believe, hitherto been described, although it is 

 very common, and I have frequently met with it. It occurs in the urin- 

 ary bladder, both of the male and female rat, and is quite distinct from 

 the species which inhabits the small intestine of the same animal. 



From the thickness of the posterior part of the body compared with 

 other species of Trichosomu, I would venture to suggest for this species 

 the name Trichosoma crassicauda. 



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

 have never found them ; the only species which has been as yet described 

 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 (Merluccius 

 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 fox it. 



