ANATOMY OF ARENTOOLA ASSIMTLIS. 777 



America). Lateral lobes of prostoniium well developed. No 

 otocysts. Five pairs of nepliridia opening- on segments 5 

 to 9. Two or more pairs of oosopbageal pouches, the 

 anterior pair long and slender or club-shaped, the others 

 shorter, usually pyriform. No pouches on the first diaphragm. 



Eecorded from the Mediterranean and from the west coast 

 of the United States. 



[e] A. cristata, Stimpson. — Seventeen chfetigerous seg- 

 ments. Eleven pairs of gills, the first on the seventh 

 segment. Otocysts, closed spherical sacs each containing a 

 single large, spherical, chitinoid otolith. Six pairs of 

 nephridia opening on segments 5 to 10. One pair of 

 oesophageal pouches cylindrical or club-shaped. Diaphrag- 

 matic pouclies (on the first diaphragm) large and finger- 

 shaped. 



Found in the Mediterranean, in the West Indies, and on the 

 eastern shores of North America south of latitude 40° N. 



IX. Summary of Results. 



1. The anatomy of Arenicola assimilis is fully de- 

 scribed for the first time. Although Ehlers states that the 

 species differs from A. marina only in the number of 

 chfetigerous segments (nineteen in the latter, twenty in the 

 former), in the position of the first gill and in the relative 

 size of the middle lobe of the prostomium, further examina- 

 tion shows that there are other important points of difference, 

 e, g. A. assimilis possesses multiple oesophageal glands 

 and has no pouches on the first diaphragm. 



2. vSpecimens of Arenicola are described from Otago 

 Harbour (New Zealand) and from the Macquarie Islands 

 which differ from the type in the number of cha^tigerous 

 segments (nineteen) and situation of the first gill. Tliero is 

 also a difference in the shape of the otoliths ; in the type they 

 are spherical or rounded, while in the New Zealand specimens 

 they are irregular. These specimens belong to a new variety 

 (var. af finis) of the species. 



