70 NOTICES OF IRISH ENTOZOA. 



and figured by Bremser. The only point of difference in- 

 deed which exists between my specimens of Ech. filicollis 

 and Ech. sphcerocephcelus is their being unarmed, though 

 even this may not perhaps be an insuperable obstacle to their 

 identity. Bremser first observed that several species which 

 are fully armed in their young state, lose a great part of their 

 spines on becoming adult. Rudolphi at first rejected that 

 idea, but at length, and from the examination of this very 

 Ech. sphcerocephalus, embraced it as an undoubted fact. — 

 " Ita nunc factum est, ut Echinorhynchos juniores cum seni- 

 oribus, armatos illos sensim in denudatos transientes." — ' Syn.' 

 p. 672. I may remark too that while in Bremser's seventh 

 plate, figure 15 represents the Ech. sphcerocephalus with the 

 head and anterior part of the body thickly armed, figure 17 

 with the head also thickly armed, but with only a few aculei 

 on the anterior of the body, figure 19 is totally destitute of 

 armature on any part of it whatever ; a pretty strong presump- 

 tion that in this species at least, the presence or the want of 

 armature is not of primary importance as a distinctive mark. 

 The specimens of Ech. sphcerocephalus examined by Brem- 

 ser and Rudolphi were sent by Natterer from Brazil, and were 

 found in the intestines of the sea pie {Hcematopus ostralegus), 1 

 and in those of some species of gull : they were of various 

 sizes, and very numerous. Rudolphi says of those from the 

 Hcematopus, — " Plurima specimina duas cum dimidia, unum 

 septem, alterum novem lineas attingunt," — 'Syn.' p. 670 ; but 

 no mention whatever is made of their neck penetrating the in- 

 testine, whence it may be concluded that they were found 

 free in the cavity ; and as we know that various Ascarides &c. 

 are sometimes found in the alimentary canal, and at other 

 times in the peritonceum, there can be nothing absurd in the 

 conjecture that this species may also occupy one or other of 

 these localities. Supposing then Ech. filicollis and Ech. 

 sphcerocephalus to be in reality the same, it is easy to con- 

 ceive that when the head is in the peritonceum it will be un- 

 armed, for there armature would be useless ; but on the con- 

 trary if attached simply to the mucous coat, then the same 

 necessity for armature would exist as in other Echinorhynchi 

 similarly placed ; it is therefore not improbable that since, 

 according to the circumstances of the growth of the animal, 

 the aculei are shed or retained ; so according to situation they 

 may be formed or not. These ideas are however only con- 

 jectural. 



1 Mr. Thompson suggests that this probably was the Hcematopus palli- 

 atus of Temminck, the Ham. ostralegus not being found, according to that 

 author, in South America. 



