PLYMOUTH MARINE INVEKTEBItATE FAUNA. 159 



TuNiCATA. The account is chieHy based upon the work of Mr. AV. 

 Garstang, but is by no means complete, as many of his records could 

 not be made available in time for publication. 



The description of the grounds has been prepared by Dr. E. J. Allen, 

 with the assistance of Mr. S. Pace. 



An alphabetical index of the grounds will be found below, and a 

 list of all those zoologists by whom records have been made on p. 172. 



E. J. A. 



•DESCRIPTION OF GROUNDS. 



ALPHABETICAL INDEX. 



The area dealt with in this report extends from the shore to a deptli 

 of from 30 to 35 fathoms and may be considered as limited on the sea- 

 ward side by a line running westwards from Bolt Head, passing a little 

 outside the Eddystone Rocks and Hand Deeps, and then drawing north- 

 wards and meeting the coast at Looe. The length of such a line is 

 about 35 miles, and the greatest breadth of the sea area included within 

 it (from Plymouth to beyond the Eddystone) is from 14 to 15 miles. 

 Roughly speaking, this area may be said to lie within a radius of 

 15 miles from the Laboratory. The area contains a number of typical 

 tidal rivers (Hamoaze, Cattewater, Yealm R.), the large sheets of enclosed 

 and sheltered sea represented by Plymouth Sound and the mouth of the 

 Yealm, and a considerable stretch of coastal water exposed to the full 

 force of the waves of the English Channel. 



Before giving the detailed list of the fauna inhabiting the area, it will 

 be convenient to review the general conditions prevailing in its difierent 

 parts. In this way it is hoped that some conception, even if it be an 

 imperfect one, of the nature of the influences which limit the distribu- 

 tion of the diirerent species may be formed by those having no personal 

 knowledge of the neighbourhood. 



