Afi'sce lla ncous. 197 



female undergoes considerable changes in becoming oviferous : the 

 segments of the body shorten ; the first segment of the tail becomes 

 more or less completely hidden beneath the seventh segment of the 

 body ; &c. These differences often deceptively simulate zoological 

 characters. — Comptes Rendus, July 8, 1878, p. 52. 



On Avenardia Priei, a Glyantic Xemertean of the West Coast 

 of France. By M. A. Giard. 



The Nemertean which forms the subject of this note measures as 

 much as 1 metre or even 1-20 metre in length when in a state of 

 repose ; when it extends itself its length may become three or four 

 times as much. Its breadth attains 2 or 3 centims. ; and the general 

 form of the body is flattened. In the contracted state the lateral 

 margins often appear undulated or notched, as is observed also in 

 the To'Hue and Ligulce. 



This worm is met with by hundreds at Pouliguen (Loire-Infe- 

 rieure), but in a peculiar station — namely, in an old canal (etier) of 

 the salt marshes, now converted into a reservoir, in which the sea- 

 water is renewed every tide. The water of this reservoir serves to 

 set in motion the wheels of an establishment managed by M. 

 Avenard. The workmen here have been acquainted with this 

 enormous Xemertean for a number of years. They meet with it, at 

 a depth of from 10 to 20 centims. in the mud, whenever they clean 

 out a portion of the reservoir. The salters, whom I have asked 

 about it, have not observed it any where else in the salt marshes. 

 It is equally unknown to the fishermen of the port of PouHguen, as 

 also to those of Croisic. 



The principal animals which inhabit the mud of the reservoir are 

 several species of Nereids (one of which is peculiar to brackish 

 waters), Pholades (P. dacti/his and P. Candida), Scrohicidaria;, flat- 

 fishes, and eels. Oysters, which have lately been introduced into 

 the reservoir, thrive there remarkably. The thousands of Nemer- 

 teans extracted from the mud during cleansing-operations are 

 devoirred with avidity by domestic ducks. 



The jSTemertean hollows out in the mud long galleries, which 

 it lines with a mucous coating, so that no earthy particle can 

 soil its epidermis. When put into the water it swims with the 

 greatest facility, by performing imdnlatory movements, giving it an 

 astonishing resemblance to an eel. Its colour, moreover, sufficiently 

 resembles that of this fish : the back is of a more or less dark 

 blackish grey, and quite black along the median line ; the belly 

 is entirely white or yellowish white. 



When taken out of the water, instead of stretching softlj', like 

 Liaeus longissimns, the animal breaks up very rapidly into a multi- 

 tude of fragments, which become smaller and smaller. When the 

 division stops, the fragments are scarcely more than 2 centims. long; 

 and each of them has acquired a rounded form, in consequence of 

 the contraction of the muscles, which gradually diminishes the open 

 surface of the section, and finally causes it to disappear entirely. 

 To obtain an entire specimen the most certain method is to throw 



