PLYMOUTH MARINE INVEliTEBEATE FAUNA. 165 



Alcijomdium gelatinosum is sometimes present in large quantities, as 

 well as Bowerbankia. Sponges also are numerous, and large numbers 

 of the smaller Polychtetes {Fhyllodoce maculat«, especially, n)ay occur 

 in great quantity) take refuge amongst the fixed organisms. Calyiitrcm 

 chijiensis is frequently found. 



Queen's Ground. This term is used in the records to indicate the 

 area extending from the Queen's Ground Buoy to the New Ground's 

 Buoy and the ground around the latter. It is really the inner margin 

 of the channel at the western entrance of the Sound. The depth 

 is 5-6 fms. The soil is mainly a coarse shell gravel, amongst which 

 are a number of large shells and rather small Hat stones. The ground 

 is very clean, there being little mud covering the stones and shells, and 

 the water is clearer and purer than the estuarine waters from the 

 Hamoaze which run through Millbay Channel. Tlie stones and shells 

 afford attachment to occasional pieces of red seaweed (the rare Stcno- 

 (jramina may be especially noted) and to many of the larger Calypto- 

 blastic Hydroids and branching Polyzoa (especially Bovxrhanhia). 

 Lamellibranchs (especially Spisula) live amongst the shell gravel, whilst 

 Portunus depurator is abundant on it. The Polychaite fauna differs 

 considerably from that found on the edge of the Asia Shoal and in 

 Millbay Channel. 



Duke Rock. Depth 4-5 fms. The grounds around the Duke 

 Eock form the western border of tlie channel at the eastern entrance 

 of the Sound. In recent years the Admiralty have carried out exten- 

 sive dredging operations in this neighbourhood, and have to a large 

 extent diminished its value as a dredging ground for scientific purposes. 

 The stones and shells which are taken here carry a similar collection of 

 animals to that found at Queen's Ground, but the shell gravel, with 

 the animals which inhabit it on the latter ground, is replaced by finer 

 muddy sand. 



Trawling Grounds of the Sound. The fine sand and mud grounds 

 of the centre of the Sound and of Jennycliff Bay are best worked with 

 small trawls of either shrimp mesh or mosquito mesii. Shrimps, 

 prawns, and small Crustacea, small fiat - fisiies, pipe - fishes, Sepiola 

 atlantica, and Bhiline aperta, are the characteristic species taken. The 

 dog-whelk (Nassa reticulata) and shore crab (Carcimts mwnas) are 

 abundant species on these grounds, but are best taken in traps. 



The Cattewater. The soil in the Cattewater (estuary of the Plym) 

 below Turncliapel is all soft mud, which can be worked with a shrimp 

 trawl. The characteristic local forms are almost exclusively shrimps, 

 prawns (especially Balamondes), Mysisjiexuosa, and Carcin us maiias. The 

 Cattewater is chiefiy useful, however, as a collecting ground, from the 

 fact that the Plymouth trawlers often throw a good deal of their refuse 



