660 Notices of Irish Entozoa. 



water over it, and in a short time the activity of its motion 

 will lessen, and the hitherto invisible rostella will begin to 

 protrude more or less rapidly. During the protrusion they 

 will be distinctly seen turning inside out, and when they re- 

 tract, (which they often do), as distinctly turning outside in. 

 They are represented as fully exserted at i, Fig. 32 ; but it is 

 to be recollected that the best engraving which could be ex- 

 ecuted would give only a faint resemblance of the exquisite 

 beauty and armature of the rostella themselves. 



It would be tedious to enter farther into detail, as the fi- 

 gures will explain better than words perhaps could, whatever 

 may farther be noticeable in the animal's appearance. Al- 

 though I found both animals separate as well as united, in 

 the intestine of the turbot, I can scarcely be satisfied that 

 the bothriated end especially, can be the ultimate state of 

 the animal; and am inclined to conjecture that it may final- 

 ly become a Bothriocephalus.* As the tumor containing 

 the species is so common in the fishes that have been men- 

 tioned, and perhaps in many others, I hope that the subject 

 will be taken up and more fully investigated by others. 



* From the circumstance of the two different individuals being conti- 

 nuous in substance with each other, the generic title Syngamus, which has 

 been applied to another entozoon characterized by a similar union, might 

 seem to be more proper than that of AnthocepJialus, but as the two indivi- 

 duals are also found separate, and as it is probable that more of their his- 

 tory will be ascertained, I have preferred, (for the present at least,) the 

 older appellation. 



Mr. Owen> in the very able article " Entozoa 1 '* in the Cyclopaedia of 

 Anatomy, has the following passage in reference to the organic junction 

 Of the male and female Syngamus trachealis. 



" In the Heteroura andropkora of Nitzch (Hersch and Gruber's Ency- 

 clopaedic, th. vi. p. 49, and th. ix. taf. 3. f. 7.) the male maintains an ha- 

 bitual connexion with the female, which has a horny prehensile process 

 for the purpose of retaining the male in this position. Here there is no 

 confluence of the substance of the bodies of the two sexes ; the individuals 

 are distinct in their superficies as in their internal organization. But this 

 singular species offers the transitional grade to that still more extraordinary 

 Entozoon, the Syngamus trachealis, in which the male is organically 

 blended by its caudal extremity with the female, immediately anterior to 

 the slit-shaped aperture of the vulva, which is situated as usual near the 

 anterior third of the body. By this union a kind of hermaphroditism is 

 produced ; but the male apparatus is furnished with its own peculiar nu- 

 trient system; and an individual animal is constituted distinct in every 

 respect, save in its terminal confluence with the body of the female. This 

 condition of animal life, which was conceived by Hunter as within the 

 circle of physiological possibilities, (see Anim. (Economy, p. 46,) has hi- 

 therto been only exemplified in this single species of Entozoon ; the dis- 

 covery of the true nature of which is due to the sagacity and patient 

 research of Dr. Charles Theodore Von Siebold." 



