ANATOMY OF ARKNICOLA ASSIMIIJS. 737 



The Anatomy of Arenicola assimilis, Elilers, 

 and of a New Variety of the Species, with 

 some Observations on tlie Post-larval Stages. 



By 



J. II. A^liwortli, D.Sc, 



Lecturer on Invertebrate Zoology in tlic University of Edinl)urgii. 



With Plates 3G and 37. 



Contents. 



PAGE 



I. Introduction ...... 737 



II. Arenicola assimilis. Elders .... 740 



III. S[jecimens of Arenicola from New Zealand . . 754 



IV. Systematic Position of A. assimilis and of the Specimens from 



New Zealand ..... 7G0 



V. Post-larval Stages of Arenicola from the Falkland Islands . 764 



VI. Adult Specimens of Arenicola from the Falkland Islands . 768 



"VII. Distribution of Arenicola assimilis . . . 772 



VIII. Specific Characters of the Caudate Arenicolidaj . . 775 



IX. Summary of Results . . . . .777 



X. Literature . . . . . .780 



I. Introduction. 



In response to my inquiry regarding the occurrence of 

 Arenicola on the shores of New Zealand^ Professor Benliani 

 kindly sent to me three specimens of this worm from Otiigo 

 Harbour, and one from the Macquarie Islands. 



The specimens were caudate Arenicolida3 resembling A. 

 marina, Linn., and A. claparedii, Levinsen, in external 

 form. A rapid examination of tlie grosser anatonn'cal 

 features of one of the Otago specimens seemed to point to its 



