26 Arenicolidae 



Polychaeta of elongate, cylindrical form, which, when adult, 

 bear gills on a number of successive chaetiferous segments; pro- 

 stomium without tentacles or palps ; peristomium without cirri, 

 followed by an achaetous segment and by a number of chaetiferous 

 segments, each of which bears dorso-laterally a tuft of capillary chaetae, 

 and, more ventrally, a row of crotchets ; an achaetous " tail " is 

 present in some species. The pharynx has no jaws, but bears series 

 of papillae, the tips of which, in large specimens, may be capped 

 with chitin ; glandular caeca, one or more pairs, are present on the 

 posterior part of the oesophagus ; coelomic septa have disappeared 

 in the region of the body in which the " stomach " is situated, but 

 septa are constantly present at the anterior border of the first, third 

 and fourth chaetiferous segments, and also in a greater or less extent 

 of the intestinal region. Nerve-cord non-ganglionated. 



TYPE GENUS. Arenicola Lamarck. 



HISTORICAL ACCOUNT. The family Telethusae J was founded by 

 Savigny for the genus Arenicola, only one species of which, 

 A. marina (then usually designated A. piscatornm Lamarck) was 

 known. 



Latreille included Branchellion a genus of leeches in this family, 

 for the sole reason that, like A. marina, it possesses gills on the middle 

 segments of the body. 



In 1833 Audouin and Edwards designated the family, in which 

 they placed only the genus Arenicola, Arenicoliens, and two years 

 later the latinised form Arenicolidae was first used in an article by 

 Johnston. These names have been adopted by most subsequent 

 writers in preference to the original family name. It is a little 

 remarkable that Johnston, after using the name Arenicolidae in his 

 papers in 1835, 1840 and 1845, reverted in his British Museum 

 Catalogue 2 to the use of the designation Telethusae. 



Several authors have attempted to add other genera to the 

 family, or to use the family name in an extended sense ; but, 

 with one exception, these changes have not been attended with 

 success. The term Arenicoliens was used by Edwards in 1838, 



1 Telethusa, the wife of Lygdus and mother of Iphis. Ovid, Metam., 

 ix, 682. 



2 The name Arenicolidae is given (p. 214) as if it were a synonym of the 

 sub-order Limivora. 



