NOTES ON CORNISH CRUSTACEA. 



293 



rarely been found in Mount's Bay, though Tregelles mentions that 

 he obtained four there in a cast-up Laminaria stem. A single 

 specimen was dredged about midway between Kynance Cove and 

 Mousehole, and it has occurred in trawl-refuse near the Wolf, 

 and from west of the Bishop at Scilly. On the north coast it 

 occurs at Zennor, in 3 to 13 fathoms at St. Ives (Vallentin), and 

 at Padstow. Females in berry are most plentiful from the 

 middle of March to the end of April, and from the end of June 

 to the beginning of August. 



The Maiidce and the Inachidce, represented in Cornwall by 

 eleven species, have the singular habit of concealing themselves 

 by attaching living fragments of stationary marine fauna and 

 flora to their shells. These at first are held in place by the 

 numerous tubercles, spines and hairy tracts with which the 

 shell is provided, but soon become permanently attached, and 

 often grow rapidly on this novel but congenial habitat. They 

 are of course cast off with the shell, but are quickly and efficiently 

 replaced. So varied are the Hydroids and Bryozoa in this 

 living disguise that Mamaia squinado in particular has always 

 been regarded in Cornwall as a regular purveyor of deep-water 

 forms for the naturalist with limited opportunities of dredging 

 in the open sea. Till the living covering is removed it is often 

 impossible to distinguish closely related species. 



Hyas coarctatas, Leach, is locally common from 10 to 45 

 fathoms on sand and gravel, but over large tracts of apparently 

 suitable sea-bottom is very thinly distributed. It occurs sparingly 

 as a rule in trawl-refuse all round the coast and at Scilly. It is 

 either nomadic or migratory, and in summer is often abundant 

 in 10 to 15 fathoms, as in Gerrans Bay in 1901, 1905 and 1908, 

 and off Helford River in 1901, 1902 and 1906. In 1903, on the 

 other hand, careful dredging over the spots favoured in 1901 

 resulted in the capture of two examples in Gerrans Bay and 

 not a single specimen at Helford. It is usually common about 

 Gorran, and is often taken in Falmouth Bay and in deepish 

 water outside Mount's Bay. At St. Ives it is abundant in sum- 

 mer in 12 to 14 fathoms (Vallentin), and has been- taken in 

 20 fathoms about eight mile3 north of Point Navax, in 5 fathoms 

 in Fistral Bay, at Harlyn Bay, and about Padstow. Females 

 occur in berry in April, July and August. H. araneus (L.), 



