J{j,U-sheUs and Mussels 6g 



well marked. The animal, too, may be at once identi- 

 fied by its difference in colour from the true Mussel. 

 The latter hjvs a creamy white tint, but this is dark 

 orange ; the foot red, Avhitish towards the thick and 

 wrinkled base. Both margins of the mantle are 

 without fringe or toothing, though covered with 

 delicate cilia. 



Its habitat is a muddy gravel at various depths 

 between low water and 80 fathoms, most plentifully 

 on our northern coasts. Its usual size is about 5 

 inches long, but it has been found over 9 inches in 

 length. Its roomy interior is a favourite resort of 

 the Pea-crab, which appears to live on the most 

 friendly terms with it, and to avoid all risk of 

 injuring its host has got rid of every one of those 

 angles and sharp edges that characterise most crabs, 

 and is now as smooth and glossy as glass, with every 

 edcre rounded. 



There are several other British species described, 

 of which one or two are possibly only juvenile 

 forms. The Bearded Horse Mussel (if. barhatus) is 

 little more than 1 inch long, with an orange or 

 scarlet shell, mostly hidden by a thick yellow-brown 

 epidermis, which on the back and front of the shell 

 is so split up as to form a fringe of thorns. Each of 

 these thorns is bearded along one side only, as 

 shown in the figure of a small portion. It 

 occurs on the south and west coasts of 

 England and Wales ; rarely on the east ; 

 also on the south and west of Ireland. Its 

 habitat is on rough ground from low water 

 to 18 fathoms. The Tulip Horse Mussel (il/. adri- 

 atica) has a broad convex shell, slightly smaller than 



