186 MYTILHLE. 



M. PHASEOLINA, Pllilippi. 



Small, never rayed ; epidermis highly polished, its byssal fila- 

 ments simple ; dorsal edge much shorter than the upper posterior 

 one ; hinge-margin with most minute internal corrugations ; 

 beaks terminal. 



Plate XLIV. fig. 3. 



Modiola phaseolina, Philippi, Mol. Sicil. vol. ii. p. 51, pi. 15, f. 14. — Jeffreys, 

 Ann. Nat. Hist. vol. xix. p. 313. 



From the simple filaments of its byssal garment, this 

 recently discovered shell incurs more risk of being con- 

 founded with Modiolus than with barbata, although they 

 are profusely disposed as in the latter, rather than scantily 

 furnished as in the former. There appears to exist a 

 considerable diversity of outline in different individuals, 

 some more nearly exhibiting the outline of one, some of the 

 other of the two species we have mentioned, but all seem 

 either devoid of dorsal angulation, or else with their angle 

 much nearer to the anterior end than in those species. 

 The valves are subventricose ; their convexity is rather 

 evenly disposed, there being scarcely any dorsal compres- 

 sion, and no posterior refusion of surface. The cuticle is 

 highly lustrous (which polish pervades its entire extent) 

 and is of a brownish-yellow, becoming paler in front of the 

 diagonal elevation. The hinder dorsal edge, which is 

 straight, ascends considerably, and is shorter than the 

 upper posterior outline ; which latter is subarcuated, and 

 runs nearly parallel to the ventral margin, in its junction 

 with which it forms a broad and rounded termination. The 

 ventral margin is swollen behind ; the lower front area is 

 very small, and does not at all project beyond the terminal 

 beaks, so that strictly speaking there is no anterior side. 



