Gordhis aquaticus. 355 



tide marks, and is of frequent occurrence. It creeps with 

 ease and tolerable quickness, and never leaves the water vo- 

 luntarily, though it can live a day at least out of it; and, unlike 

 most marine insects, it is not killed by immersion in fresh 

 water. It is much infested with infusory animalcules. 



There is no genus characterised by Duges to which the A. 

 Basten can be conveniently referred ; but it would be very 

 imprudent on my part to propose the establishment of another 

 for its reception. The species is probably synonymous with 

 the A'caxus zosterae of Turt. GmeL, iii. 705. ; who does not 

 quote the authority on which it is introduced into the System 

 of Nature, though the habitat "seas of Norway" leads to the 

 conjecture that Muller is the individual from whom he has 

 borrowed his jejune description. 



Go'rdius aqua'ticls. {Jig. 52.) 



So much has been said in this Magazine [p. 241 — 243., and 

 the other places there indicated] of the G. aquaticus, and so 

 very few of those who have written about it seem to knew 

 the animal, that I am tempted to give a figure, and some 

 short account, of the veritable worm ; which, though common 

 enough, is less so than the Filaria, frequently mistaken for it, 

 and to which, so far as I can remember, all the notices scat- 

 tered through the volumes of the Magazine truly appertain. 



Synonymes. — Gordius pallidus ; cauda capiteque nigris Linn., Suec. 363. ; 

 G. aquaticus Lin., Turt., iv. 57.; Turt. Brit. Faun., 130. ; Stew. Eleir., 

 ii. 353. ; Lam. Anim. s. Vert., iii. 220. ; Flem. Phil. Z00L, ii. 605 ; 

 Cuv. Reg. Anim., iii. 217. ; Baird in Hist. Berw. Nat. Club, p. 23. 



Hab. — Slowly running and stagnant waters, in summer. 



Desc. — The body is from 6 to 10 in. long, of the thickness 

 of a hog's bristle, exactly filiform, rigid and incompressible, 

 smooth, of a uniform blackish or yellowish brown colour, some- 

 times paler on the ventral surface, and the tips always a shade 

 darker. The head is obtusely conical, with a simple circular 

 terminal pore for a mouth, from which a sort of membrane 

 can be forced by pressure. The skin is smooth, minutely 

 areolar, as is very evident when it is partially dried, and 

 marked with a few obscure circular plaits, perhaps produced 

 by the process of drying. Within an inch of the tail, there 



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