374 PROCEEDINGS OF THE ACADEMY OF [May, 



Clitellio arenarius Miiller. To the latter conclusion I have been much 

 assisted by Prof. Verrill's great kindness in sending to me for study his 

 entire collection of marine oligochsetes, including many bottles labelled 

 by him as Clitellio irrorata. Although this material was collected from 

 25 to 30 years ago, and had since been subjected to all of the vicissitudes 

 of preservation in small vials of alcohol, it was possible to determine 

 most of the specimens, and as a result to considerably extend the known 

 range along our coasts of several species. For this privilege I am much 

 indebted to Prof. Verrill. 



In the present paper are noticed ten species representing three fami- 

 lies, as follows: Naiidae, Paranais littoralis; Tubificidse, Clitellio are- 

 narius, Monopylephorus glaher, M. parvus, Tuhifex irroratus, T. bene- 

 deni, T. hamatiis and Limnodrilus suhsahus; Enchj'trseidse, Enchytroeus 

 albidiis and Lumhricilliis agilis. Of these P. littoralis, C. arenarius, 

 M. parvus, T. henedeni and E. albidus are European species, but only 

 the first and last have hitherto been recognized on our shores. Tubifex 

 irroratus is the residiumi of Verrill's C. irrorata and the remaining four 

 are new, but have more or less closely related representatives in other 

 parts of the world. It needs to be remarked that very few of these 

 worms are really marine ; they are more or less recent migrants from a 

 rich limicoline or terrestrial oligochsete fauna. The naids and tubificids 

 are derivatives of the former which have been carried down the streams 

 into bays and estuaries and have spread through the brackish waters 

 and along the littoral zone. In their new habitat they have undergone 

 modifications that are sometimes considered to have generic value. A 

 case of especial interest is that of the brackish water Limnodrilrus sub- 

 salsus, which is the only species of this large genus that has been re- 

 corded as occurring out of fresh water. As pointed out in the systematic 

 part of the paper, especially under Monopylephorus glaber, some of the 

 tubificids burrow in soil saturated with fresh water from springs, and 

 are experimentally shown to take more kindly to pure fresh water than 

 to salt water of sea density. The enchytrseids are more particularly 

 strand forms which inhabit the marine vegetation thrown by the waves 

 upon the beach. They enter the littoral zone, but are often found in 

 large numbers quite above the reach of the waves at high tide, particu- 

 larly diu-ing rain storms. They are undoubtedly derived from terres- 

 trial or amphibious forms that have found a favorable environment on 

 the seashore. Enchytraus albidus, at least, is found in garden and wood 

 soil also, but may have l^een introduced through the use of eel grass for 

 fertilizer. 



The species of Tubificidse described in this paper, as well as some of 



