L.M.B.C. MEiMOIRS 



No. XVII. PECTEN. 



BY 



W. J. DAKIX, M.Sc, 



1851 Exhibition Scholar, University of Liverpool. 



INTRODUCTION. 



Although the greater part of the following account of 

 this type applies to the anatomy and histology of Pecfen 

 maximus, the very common smaller species P. opercidaris 

 has also been investigated. Some details in which the 

 latter ditfers from P. maximus are mentioned in the text, 

 but, on the whole, these differences are but slight, and 

 either species may be dissected and examined while using 

 this Memoir. 



The work has been carried out chiefly in the Zoology 

 Department of the University of Liverpool and at the 

 Port Erin Biological Station, Isle of Man. The chemical 

 work was done at Larne. Co. Antrim, and some of the 

 observations on the sense organs at Kiel. My thanks are 

 due to Professor Herdman for his valuable advice, and 

 for aid in obtaining living material by dredging at Port 

 Erin ; also to the Larne Aluminium Company for per- 

 mission to use their chemical laboratory ; and finally to 

 Mr. Chadwick, Curator of the Port Erin Biological 

 Station. 



TAXONOMY AND DISTRIBUTION. 



Pecten maximus and P. operculnris are two of ^i- 

 common British species of the genus Pecten, and are 

 known in some places as '' scallops. Pecten is the most 



