HERMELLIFORMIA MYZOSTOMARIA 



341 



common, adhering to Fucus, shells, and other objects. 

 sented by fossils in the Palaeozoic 

 rocks. Cosmopolitan. 



Pro tu la (Psygmobranchus ) 



tubularia Mont, is a Serpulid 

 without an operculum ; it forms 

 a straight or slightly and irregu- 

 larly curved tube. Atlantic and 

 Mediterranean. Salmacina dys- 

 tcri Huxley has no operculum ; 

 it is a small worm incrusting 

 seaweeds, or forming masses like 

 Filigrana. 



Sub-Order 2. Hermelliformia. 



The single family Hermellidae 

 is represented by two species 

 Sabcllaria alveolata L., which is 



littoral, and S. spinulo&a Leuck., p xa 134. 



occurring in 10 to 30 fathoms. 



It is repre- 



S. alveolata l is about an inch 

 long ; the thorax is purple, the 

 abdomen yellow to red. The 

 narrow caudal region is bent 

 sharply forwards, so that the 

 anus, situated at its tip, comes to 

 lie at the orifice of the tube, 



'spirorbis. A, the shell, en- 

 larged. B, the animal, x 50. c, 

 Peristomial collar ; e, eggs in the brood 

 pouch at the end of the operculum ; 

 g, gills ; m, thoracic membrane (char- 

 acteristic of Serpulidae) ; n, the single 

 pair of thoracic nephridia opening by 

 a median dorsal pore beneath the 

 collar (common to all Sabelliformia) ; 

 o, ova in the anterior abdominal seg- 

 ments ; op, operculum ; s, sperma- 

 tozoa . in the hinder abdominal seg- 

 ments ; st, stomach. (From Clapa- 

 rede.) 



which is irregular and sandy. 



Great numbers of the animals live together, so that the masses 



of their tubes may be 2 or 3 feet thick and several feet long. 



They are well seen on the shore, at Paignton, near Torquay, and 



on Hilbre Island, off the Cheshire coast. North Sea, Atlantic, 



Mediterranean. 



Order III. Myzostomaria. 2 



These animals are parasitic on Crinoids or Asteroids. 3 The 



1 For the anatomy see Meyer, ML Stat. Neapel, vii. 1887 ; see also above, p. 306. 



2 von Graff, " Myzostomida," "Challenger" Reports, part 27, vol. x. 1884 ; and 

 "Supplement," part 61, vol. xx. 1887. 



3 Marenzeller, Anz. Akad. Wien, xxxii. p. 192. 



