116 MYTILID.E. 



black epidermis and quite of a purple colour inside to- 

 wards the broader end, and having the valves less raised 

 near the hinge and compressed in front. The M. bar- 

 batus of his ' Prodromus ' is probably the young of M. 

 modiolus. Linne also described the present species in 

 his ' Fauna Suecica/ but not with sufficient precision. 

 It is the Modiola Gibbsii of Leach's ( Zoological Miscel- 

 lany/ and Mytilus Gibbsianus of his work on British 

 Mollusca edited by Dr. Gray. 



4. M. Adria'ticus *, Lamarck. 



Modiola adriatica, Lam. An. s. Vert. vi. p. 112. Modiola tulijpa, F. & H. 

 ii. p. 187, pi. xlv. f. 7 ; pi. xlviii. f. 6 ; and (animal) pi. Q. f. 6. 



Body pale red with a yellowish tint : mantle forming two 

 incomplete very wide and short tubes, which are of equal length 

 and scarcely separated from each other ; the mouth of each 

 tube is fringed with about twenty close-set short cirri : gills 

 pale brown : foot long, flattish and slender, divided lengthwise 

 by a flake-white line, and having a byssal groove which in- 

 creases in depth from point to heel : byssus strong, yellowish. 



Shell oval, inclining to rhomboidal, bluntly pointed or 

 rounded at the smaller end, and expanding outwards as in the 

 last species, convex, extremely gibbous towards the beaks, thin 

 and of a delicate texture, glossy : sculpture, fine but irregular 

 lines of growth : colour yellowish, with usually rose- red rays 

 on the posterior half, occasionally purple ; these rays or streaks 

 resemble those of a tulip, and are very beautiful ; they are 

 variously arranged, and sometimes broken or interrupted : 

 epidermis thin, yellowish, and like a coat of varnish, some- 

 times a little exfoliated on the dorsal side and in front, and 

 forming slight hairs, marked lengthwise by minute lines or 

 scratches : margins thin, straight on the ventral side, angu- 

 lated behind and rising into a shoulder or sharp keel towards 

 which the posterior sides are compressed, semicircular in front : 

 byssal sinus represented by a narrow slit : beaks small, close 

 together, inflected, placed at comparatively a considerable dis- 

 tance from the anterior margin : hinge-line gently curved, 

 occupying about one-half of the dorsal margin : ligament nar- 



* Inhabiting the Adriatic. 



