94 MOLLUSCA. 



Myt. edulis, L. This common Muscle is frequently seen sus- 

 pended in extended clusters, along the whole coast of France, 

 to rocks, piles, &c. &c. It forms a considerable item of food, 

 but is dangerous if eaten to excess.* , 



Some of them are found fossilf. In the 



MODIOLUS, Lam. 



Separated from the Mytili by Lamarck, the summit is lower and 

 near the third of the hinge. This summit is also more salient and 

 rounded, approximating the Modioli more closely to the ordinary form 

 of the bivalvesj. We may also separate from the Mytili the 



LlTHODOMUS, CUV., 



In which the shell is oblong, and almost equally rounded at the two 

 ends, the summit being close to the anterior extremity. The species 

 of this subgenus at first simply attach themselves to stones like 

 the common Mytili ; subsequently, however, they perforate and 

 excavate them in order to form cells, into which they enter, and 

 which they never quit afterwards. Once entered, their byssus ceases 

 to grow. 



One of them, the Mytilus lithophagus , L., Chemn., VIII, 

 Ixxxii, 729, 730, is very common in the Mediterranean, where 

 from its peppery taste it is esteemed as food. 



A second, Modiolo caudigera, Encyc. pi. 221, f. 8, has a very 

 hard small appendage at the posterior extremity of each valve, 

 which perhaps enables it to excavate its habitatation. 



ANODONTEA, Brug. 

 The anterior angle rounded like the posterior, and that next to the 



* Add, Mytilus barbatus, L., Chemn., VIII, Ixxxiv, 749 ; M. angulatus, Ib., 756 ; 

 M. bidens, Ib., 742, 745 ; M. afer, Ib.,lxxxiii, 739 741 ; M. smaragdinus, Ib., 

 745 ; M. versicolor, Ib., 748 ; M. lineatus, 753 ; M. exustus, Ib., 754 ; M. stria- 

 tulus, Ib., 744 ; M. bilocularis, Ib., Ixxxii, 736 ; M. vulgaris, Ib., 732 ; M. sex- 

 afilis, Rumph., Mus. xlvi, D ; M.fulgidus, Argenv. xxii, D ; probably the same as 

 the Mya perna, Gm., Cbemn., VIII, Ixxxiii, 738 ; M. azureus, Ib., H ; M. muri- 

 nus, Ib., K ; M. puniceus, Adans., I, xv, 2 ; M. niger, Ib., 3 ; M. lavigatus, Ib., 

 4, &c.: some of these, however, may be mere varieties. 



f* M. Brongniart has formed them into a subgenus by the name of MYTILOIDA, 

 Ap. Cuv. Oss. Foss. tome II, pi. iii, f. 4. 



J Mytilus modiolus, Chemn., VIII, Ixxxv, 757 760, and that of Mull., Zool. 

 Lan., II, liii, which appears to be another species; M. discors, Chemn., VIII, 

 Ixxxiv, 764 768 ; M. testaceous, Knorr., Vergn., IV, v. 4, &c. 



M. Sowerby doubts this fact, which is, however, well attested by M. Poli from 

 ocular demonstration Test. Neap., II, p. 215. The pi. xxxii of the same work, fig. 

 10, 11, 12, 13, also proves that the animal resembles that of a Mytilus, and not that 

 of a Pholas or a Petricola. 



The mode in which the Lithodomi, Pholades, Petricola, and some other bivalves 

 perforate stones, has been the subject of much discussion ; some of the disputants 

 holding it to be effected by the mechanical action of the valves, and others simply 

 by solution. See the Me"m. of M. Flcuriau de Bellcvue, Journ. de Phys., an X, p. 

 345 ; Poli, Test. Neap., II, 215, and Edw. Osier, Phil. Trans, part III, 1826, p. 

 342. All things considered, the first of these opinions, whatever be the difficulties 

 it presents, seems to us to come nearest to the truth. 



