236 MALACOZOA. TKOriOPODA. LAMELLIBRANCHIATA. 



D. Mytilus edulis anguldtus. Ungulate Eatable Mussel. 



Shell ovato-trigonal, rather thick, opaque ; the umbones 

 small, rather pointed, somewhat curved, the anterior dorsal slope 

 straight, forming a prominent angle with the posterior dorsal, 

 which is much curved ; the ventral nearly straight ; the epi- 

 dermis dusky, usually more or less abraded ; the shell dull 

 blue. From an inch to two inches or more in length. 



This variety passes directly into the last. It is found in 

 pools left in rocky places by the tide, often under stones, but 

 also in crevices. Common on the Girdleness, at Aberdeen. 



Mytilus angulatus. Alder. Mytilus solitarius. Mark. Mytilus 

 subsaxatilis. Williamson, Mag. Nat. Hist. vh. 353. f. 48. 



E. Mytilus edulis pusillus. Dwarf Eatable Mussel. 



Shell oblong, thick or thin, opaque or pellucid, convex or 

 compressed, of various colours. 



Crowded on rocks, stones, shells, piles, and other objects. 



The species is abundant along our coasts : of small size and 

 densely crowded, on the rocky shores ; large on hardish- 

 ground at the mouths of rivers ; solitary, incurved individuals 

 in fissures of rocks ; small oblong, very convex individuals 

 compacted on rocks, stones, and wooden piles. The young 

 clustered on corallines, fuci, rocks, stones, piles, stake-nets, 

 ropes, and other immersed bodies. 



The mussel affords a rather pleasant article of food ; but in 

 Summer or Autumn, when, from accidental circumstances, it 

 has become diseased, it is apt to cause derangement of the 

 digestive functions, sometimes followed by affection of the 

 nervous system, and even death. It affords good bait for had- 

 docks and other fishes ; but is not obtained on the Aberdeen- 

 shire coasts in sufficient quantity for that purpose. The Estu- 

 ary of the Ythan supplies the Collieston fishers ; but those of 

 Aberdeen, not finding a sufficient supply at the mouth of the 

 harbour, import mussels from various distant places, especially 

 Hull and Dundee. Small pearls, of very inferior colour and 

 lustre, are often found abundantly in this species. 



GENUS 2. MODIOLA. MODIOLE. 



Animal obovate or elliptical, compressed behind, 

 otherwise as in Mytilus. 



Shell elongated, equivalve, inequilateral, obovate, con- 



