OF NORTHUMBERLAND AND DURHAM. 81 



Lowlights being found insufficient for their supply. The Mus- 

 sels got on these occasions are kept alive in pools among the rocks, 

 built round with loose stones. 



85. MODIOLA, Lamarck. 

 * Smooth. 



1. M. VULGARIS, Flem. 



Mytilus modiolus, Mont. Test. Brit. 163. 

 Var. Mytilus harbatus, Mont. Test. Brit. 161. 

 From deep water, common. The variety is frequently found 

 on rocky ground, near low-water mark. 



It is remarkable that the large form of M. vulgaris is always 

 found with us in deep water, never approaching the shore, and 

 even rare in a depth of 20 or 30 fathoms, while on the western 

 coasts it is found frequently in shallow water, and even close to 

 low-water mark. 



** Ribbed at each end (Lanistina, Gray). 



2. M. NIGRA, Gray. 



Mytilus descrepans, large var., Mont. Test. Brit. Supp. Q5, 



t. 2Q, £ 4. 

 Modiola nigra, Thorpe Brit. Mar. Conch. 249, I 58. 

 From deep water, rare. Cullercoats. — J. A. Whitburn. — 

 Hev. G. C. Ahhes. Mr. Howse dredged it alive in 17 fathoms. 

 Mr. King has also got it from the fishing boats. 



The animal of this species is transparent white, with the mar- 

 gin of the cloak and siphon speckled with brown and opake 

 white. 



3. M. DESCREPANS, Mont. 



Mytilus descrepans, Mont. Test. Brit. 169. 



At the roots of sea-weeds between tide -marks, common. Also 

 in corallines from deeper water, where it attains a much larger size. 



The animal is white, and, assisted by its long strap-shaped 

 foot, can move about pretty quickly ; but it generally prefers a 

 stationary life, and forms for itself a kind of nest or case by 

 stitching together the small sea-weeds or corallines with its 

 byssal threads ; here it remains attached by its byssus awaiting 

 the food that may come within its reach. 



