tae CLASS XII. 
to form a small anal tentaculiferous canal. Labial palps four, 
elongate, lanceolate. 
Mytilus Lam. Points terminal. 
Sp. Mytilus edulis L., Baster Natuurk, Vitsp. 1. 117—127, Tab. Xt. figs. 
g—11, Cuv. R. Ani., éd. ill., Mollusq. Pl. 89, mussel. The shell is elongate 
and, after the epidermis has been removed, purplish-blue. This species is 
found in the North Sea and the Mediterranean. Mussels grow quickly, 
and are already edible in the second year. Sometimes they are injurious, 
and in the spring with us they are less pleasant to the taste; as experience 
in Zealand has taught, they are best from July to January. Some con- 
stitutions cannot endure mussels, and this has in part contributed to give 
these conchifers a bad name, as though they were sometimes poisonous. 
The eggs are not taken up by the gills, as in Anodonta and Unio, but by 
the mantle. Compare for the anatomy of the mussel A. DE HEIDE Ana- 
tome Mytili. Amstelod. 1683, 8vo, Pout Test. utr. Sicil. 1. pp. 197—207, 
Tab. 31, G. R. TrREvIRANUS Zettschr. f. Physiol. 1. 1824, 8s. 41—47, Tab. 
v. figs. 26—29. For the other species of this genus, see LAMARCK Hist. 
nat. des Ani. s. v. and DESHAYES Encycl. méth., Vers. 11. pp. 557 and foll. 
Modiola Lam. Points sublateral. 
Sp. Modiola tulipa Lam., Encycl. méth., Vers. Pl. 221, fig. 1, from the gulf 
of Mexico, &c. 
There are elongated species, that penetrate into stones, of which CUVIER 
forms the sub-genus Lithodomus. Sp. Mytilus lithophagus L., Mod. litho- 
phaga LaM., Buainv. Malac. Pl. 64, fig. 4.1 
Tichogonia RossM., Dreissena V. BENEDEN. Shell elongate, 
trigonal, inflated posteriorly, flat or subconcave anteriorly. Points 
terminal; internal septum near the points. Mantle anteriorly con- 
crete, excised for foot. Anal trachea distinct. 
Sp. Tichogonia Chemnitzii ROSSMAESSLER, Mytilus polymorphus fluviatilis 
Pau, Mytilus Hagenii V. BAER, DESHAYES Conchyl. Pl. 37, figs. g—11, 
&c. Patuas first discovered this species in the Wolga; in Holland it was 
first met with in the sea of Haarlem by H. W, WaAarbDENBURG, who 
described it under the name of Mytilus lineatus LAM., with which, however, 
it does not agree (Ann. Acad. Lugd. Bat. 1826, 1827, Comment. de Moll. 
indig.) ; it occurs also round Leyden in the Cingels and elsewhere. VAN 
BrNEDEN has given a further account of this animal in Ann. des Sc. nat., 
1 In the columns, which are the remains of the temple of Serapis in the gulf of 
Baiz, an entire segment is seen, which is perforated by these animals, about 22 feet 
above the surface of the sea; see Pout Test. utr. Sic. 11. p. 216; recent geology has 
borrowed a proof from this of the depression and upheaving of the ground from which 
so many phenomena receive their explanation. Compare the well-known work of 
Lyre Principles of Geology. 
