118 MYTILIDJE. 



gas generated in the process of decay. The thin texture 

 of the shell, the coloured rays, and the greater distance 

 of the beaks from the anterior margin will readily serve 

 to distinguish this species from the young of M. modio- 

 lus. It differs from M. barbatus in its rhomboidal 

 shape, in being much more convex, and its paler colour, 

 as well as in the rays, position of the beaks, sculpture, 

 and epidermis. 



M. Adriaticus appears to have been known to Mon- 

 tagu ; for in his account of M . barbatus he says, " A 

 variety is faintly radiated." The Modiola tulipa of 

 Lamarck (for which the British species has been mis- 

 taken) is described as a native of the American seas, 

 and a variety of it as coming from New Holland. The 

 tropical shell is of a different shape and substance from 

 ours, and they only agree in the style of colouring. 

 Lamarck pointed out the distinction between them. 

 The present species may be the Mytilus pictus of Gmelin 

 (from Bonanni), which is said to inhabit the coasts of 

 Spain ; but the diagnosis given by him is too slight for 

 the purpose of identification, and the Modiola picta of 

 Lamarck is another species and better known. In 

 Thorpe's ' Marine Conchology ' our shell has the appro- 

 priate name of " radiata" which appears to have been 

 given to it by the late Captain Brown. 



5. M. phaseoli'nus *, Philippi. 



Modiola phaseolina, Phil. Moll. Sic. ii. p. 51, tab. xv. f. 14; F. & H.ii. 

 p. 186, pi. xliv. f. 3. 



Body reddish-brown : foot long and cylindrical : hyssus 

 strong, light horncolour. 



Shell conformable with its name, obliquely expanding from 

 * Shaped like a kidney-bean. 



