FLUTE-MOUTHS OR TOBACCO-PIPE FISHES. 57 



other marine animals such as Holothurians (more familiarly 

 known as Sea-Cucumbers, Beche-de-mer or Trepang) ; and 

 bivalve Mollusks such as the mother-o'-pearl shells and 

 certain mussel-shells. They are perfectly harmless to their 

 host, and merely seek for themselves a safe habitation ; 

 being in fact "lodgers." Boulenger writing of the genus 

 Fierasfer says : "It has been observed to enter Holothurians 

 by the posterior or anal aperture, either head first or tail 

 foremost; in the latter case availing itself of the suction 

 which takes place alternately with the expulsion of water 

 by that orifice ; it remains near the anus, from which it pro- 

 jects its head in search of food outside its host. It is 

 neither a true parasite, nor a commensal or mutualist in the 

 sense given to these terms by Van Beneden, but simply a 

 lodger, 'inquilino,' as Emery puts it. Semper, however, 

 regards Encheliophis vermicularis as a true parasite, feed- 

 ing on the viscera of the Holothurian in which it lives." 



Saville-Kent mentions the occurrence of these peculiar 

 and interesting fishes in the bodies of the commercial Holo- 

 thurians known as "Beche-de-mer," on the Queensland 

 coast; and I have known them to be taken from mussel- 

 shells on the coast of New South Wales. Occasionally, 

 when inhabiting the shells of bivalves they have been known 

 to become embedded in the substance of the shell itself by 

 the deposition of the pearly matter (which is secreted bv 

 the mollusk) over their bodies. 



FLUTE-MOUTHS OR TOBACCO-PIPE FISHES. 



(Family: Fistularndcp. .) 



THE "Flute-mouths" are fishes of greatly elongated form; 

 the foremost bones of the skull being greatly drawn out to 

 form a long tube, terminating in a small, narrow mouth. 

 They are usually scaleless. They are often termed "Pipe- 

 fishes," a name which should properly speaking be re- 

 stricted to members of the family Syngnathidce (page 59). 



