THE ANATOMY OF SOALlBREGMA INFLATUM. 303 



13. The Scalibregmidge resemble tlie Ai'enicolidjB and 

 Opheliidas in several respects, but several of these characters 

 may be largely due to the limnivorous mode of life of the 

 members of these three families. The following characters 

 are common to them : — the spacious coelom non-septate in the 

 middle region of the body; the eversible pharynx followed 

 by an oesophagus bearing a pair of glandular outgrowths ; a 

 dilated stomach with glandular walls and a straight intestine 

 with a ciliated ventral groove ; the blood-vessels of the 

 middle region of the gut are arranged so as to allow the 

 swinging movement of the stomach. 



The Scalibregmidae agree with the Ai'enicolidee also in the 

 annulation and sculpturing of the body-wall, the prostomium, 

 the brain, and non-ganglionated nerve-cord. They differ in 

 their parapodia, seta3, the position of the gil's, the heart, and 

 the nephridia. 



The Scalibregmidse resemble the Opheliid^ in their mus- 

 culature, the non-ganglionated nerve-cord, and the circula- 

 tory system ; but they differ in their prostomia, nephridia, 

 parapodia, and setae. 



The Scalibreginidaa, although allied to some extent to the 

 Arenicolido3, and to a less degree to the Opheliidae, form a 

 separate and compact family, one of the most characteristic 

 features of which is the presence of the peculiar furcate setae 

 in the parapodia. 



22. LiTERATUEE. 



1843. Kathke, II. — "Beitriige zur Fauna Norwegens," 'Nova Acta Aca- 

 demise Caesarese Leopoldino-Carolinae, Nature Curiosorum,' tome 

 XX, p. 1S2. Breslau, Bonn, 1843. 



1811. Oeksted, A, S. — " Zur Classification der Annulaten, niit Besclireibung 

 eiuiger neuer oder imzulanglicli bekannter Gattungen und Arten," 

 ' Arcliiv fiir Naturgescliichte,' Jalirgaug x, Band i, p. 99. Berlin, 

 1841. 



