FROM THE EDDYSTONE GROUNDS TO START POINT. 387 



"Under the head of 'undetermined' must be classed the alkalies, any- 

 slight traces of metallic oxides, and a small residue of COg left after ignition, 



"All the samples were fairly thoroughly washed before analysis to remove 

 salts derived from sea-water, and were desiccated before ignition." 



Section V. 

 DESCKIPTION OF THE GROUNDS INVESTIGATED. 



The grounds from the Eddystone to Start Point lying in the neigh- 

 bourhood of the 30-fathom line fall naturally into four groups. The 

 grounds around the Eddystone rocks, comprised within a circle of 

 about four miles radius, having the lighthouse for its centre, are for 

 the most part coarse grounds, with bottom-deposits of gravel or broken 

 shell mixed with more or less mud or fine sand. Towards the outer 

 limit of the circle the deposits become more and more sandy in nature. 

 These grounds will be referred to in a general way as the Eddystone 

 Grounds. (See Chart I.) South of Bolt Head the bottom-deposit is 

 broken shell-gravel, and the ground here will be named the Bolt Head 

 Shell-gravel Ground. (Chart I., Ground XVII.) Between the Eddystone 

 Grounds and the Bolt Head Shell-gravel is a stretch of fine sand, the 

 Eddjjstone Trawling Ground, the inner or northern portion of which 

 will be distinguished as the Inner Eddystone Trawling Ground, the 

 outer or southern portion as the Outer Eddystone Trawling Ground. 

 (Chart I., Grounds I. and II.). Between Prawle Point and the Start 

 is a patch of ground with many stones, the Prawle Stony Ground. 

 (Chart I., Ground XVIII.) 



The lists of species living on the various grounds will be arranged 

 according to zoological groups, but in the description of the fauna of 

 each ground, which precedes the list, the species will be grouped 

 according to their general habit, the following kinds being dis- 

 tinguished : — 



1. Burrowing species. 



2. Fixed and clinging species. 



3. Wandering or free species. 



Associated species will in all cases be ranged with their hosts, the 

 host being, in the case of fixed and burrowing animals, the one most 

 intimately connected with the bottom-deposit, in the case of wandering 

 species, the one having the greater powers of locomotion. It will 

 be found that the burrowing and fixed species, with their associates, 

 are the most restricted in distribution by the nature of the bottom- 

 deposit, whilst the wandering species may exist upon bottoms of many 



