58 MOLLUSCA FROM THE CRAG. 



determine its specific character, and it was introduced into my Catalogue as belonging 

 with doubt to this species. 



In the recent state this shell is thick and strong, but my specimens differ 

 materially in that character, and are particularly fragile. This species exhibits a 

 very considerable degree of variation in its outward form or proportional dimen- 

 sions, as may be observed in the specimens figured, but a similar variability is 

 shown in the living shell : the two forms may be considered as belonging to one 

 species, and there can be little doubt of its identity with the shell now common in our 

 own seas. My specimens were all found at one locality in association with a bed of 

 Myt. edulis. British Conchologists give it vertical range from low water mark to 

 sixty fathoms. 



I have introduced as a synonym M. grandis Phil., believing it not to differ 

 specifically from the British shell : some fossil specimens from Sicily (for which I am 

 much indebted to Madame Power) in my cabinet, presumed to be the same as 

 Philippi's species, have no character whereby they can be justly separated from the 

 shell found upon the coast of Massachusetts. The size of the Mediterranean fossil is 

 not sufficient for specific distinction, as a specimen of modiolus, measuring seven 

 inches, is recorded by Captain Brown to have been obtained by a fisherman near the 

 Bell Rock, on the coast of Forfarshire. 



2. MODIOLA BARBATA, Linn&us. Tab. VIII, fig. 2. 



MYTILUS BARBATUS. Linn. Syst. Nat., ed. 12, p. 1156, sec. Forb. and Hani. 

 Poll. Test. Sicil., vol. ii, p. 210, pi. 32, figs. 6, 7, 1795. 

 MODIOLA BARBATA. Lam. Hist, des An. Sans. Vert., t. vi, p. 114, 1818. 

 Phil. En. Moll. Sic., vol. i, p. 70, and vol. ii, p. 50. 



Forbes. Report. ^Egean Invert., p. 180, 1843. 



Forb. and Hani. Hist, of Brit. Moll., vol. ii, p. 190, pi. 44, fig. 4. 

 GIBBSII. Leach. Zool. Misc., vol. ii, p. 34, pi. 72, fig. 2, 1815. 

 Turt. Brit. Biv., p. 200, 1822. 

 Brown. Brit. Conch. Illust., pi. 29, fig. 7, 1827. 

 Ency. Meth., pi. 218, fig. 6. 



Spec. Char. Testa tenui, ovato-oUongd, extremitate compressiusculd, antice brevissimd, 

 postice dilatatdy subangulatd ; lineis incrementibus ornata. 



Shell thin, of an oblong-ovate form, posterior portion somewhat compressed, dilated 

 and sub-angulated, anterior extremity very short, concentrically striated, or lines of 

 increase distinct and prominent. 



Locality. Red Crag, Walton Naze. Recent, British and Mediterranean Seas. 



About half a dozen specimens from the Red Crag, at Walton on the Naze, appear 

 precisely in form to resemble what the authors of the ' Hist, of Brit. Mollusca,' seem 

 to consider as entitled to specific distinction, and presuming they have good data for 

 their determination, I have separated this from where it had been previously placed, 



