74 PROCEEDINGS OF THE ACADEMY OF [1890. 



Ill the collection of the Academy are six specimens from the 

 INIanatee River on the West Coast of Florida, which, although 

 presenting some slight differences, I regard as a variety o^ Arenicola 

 cristata. They have no papillse on the ventral surface of the caudal 

 segments ; the distal ends of the ventral bristles are not serrated and 

 the secondary branchiae have fewer tufts and are less regularly 

 arranged. The specimens are small, the longest about 140 mm. in 

 length, and may be immature. Ehlers^ in his work on Florida- 

 Annelids has already recorded this species from Florida under the 

 synonym of Arenicola antillensis. 



On account of the impossibility of drawing any sharp lines of 

 demarcation between the forms from the INIediterranean, New Jersey, 

 Florida and the West Indies, I venture to believe that they must be 

 regarded as representing one species, having an unusually wide 

 distribution. 



From my study of the other species of the genus in connection 

 with these forms from the New Jersey coast, I incline to the view put 

 forward by Dr. von Marenzeller,^ who, not including Arenicola cristata 

 and its synonym, Arenicola antillensis, reduces all the species of the 

 genus to two : — Arenicola marina, L. and Arenicola ecaudata, John- 

 .ston. The sixteen species of the genus which have been described 

 may therefore be reduced to the following three : 



Arenicola marina L. 6 prebranchial and 1 3 branchial segments, 

 secondary branchire with 3 or 4 pairs of lateral tufts. Europe, 

 Greenland, New England, Vancouver Island, Mediterranean, South 

 Africa, Chili (Coquimbo). 



Arenicola ecaudata, Johnston. 11-15 prebranchial and 13- 

 40 branchial segments ; secondary branchiae, arborescent. 



Europe, Mediterranean, Black Sea. 



Arenicola cristata, Stimpson. 6 prebranchial and 1 1 branchial 

 segments ; secondary branchiae, plumose. 



West Indies, Florida, South Carolina, New Jersey, Mediterranean. 



The occurrence of Arenicola marina on the northwest coast of 

 Alaska renders it i^robable that it will also be found upon the arctic 

 shores of Europe and Asia. From northwest Alaska it has un- 

 doubtedly passed southward to Vancouver Island through Behring 

 Strait, the western Gate of the North. Its distribution north and 



1 " Florida-Anneliden," Mem. Mus. Comp. Zool., Vol. xv, p. 173. 



2 Zoologische Jalirbiichef, Bd. 3, pp. 12-15. 



