732 CLASS xii. 



to form a small anal tentaculiferous canal. Labial palps four, 

 elongate, lanceolate. 



Mytilus LAM. Points terminal. 



Sp. Mytilus edulis L., EASTER NatuurTc. Uitsp. i. 117 127, Tab. xi. figs. 

 9 n, Cuv. R. Ani., ed. ill., Mollusq. PI. 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 My till . Amstelod. 1683, 8vo, POLI Test. utr. Sicil. n. pp. 197 207, 

 Tab. 31, G. B. TREVIRANUS ZeitscJir. f. Physiol. I. 1824, s. 4147, Tab. 

 v. figs. 26 29. For the other species of this genus, see LAMARCK Hist, 

 nat. des Ani. s. v. and DESHAYES Encycl. metJi., Vers. n. pp. 557 and foil. 



Modiola LAM. Points sublateraL 



Sp. Modiola tulipa LAM., Encycl. meth., Vers. PI. 221, fig. i, from the gulf 

 of Mexico, &c. 



There are elongated species, that penetrate into stones/ of which CDVIER 

 forms the sub-genus Lithodomus. Sp. Mytilus lithophagus L., Mod. litho- 

 phaga LAM., BLAINV. Malac. PL 64, fig. 4. 1 



Ticlioyonia BOSSM., 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 CJiemnitzii ROSSMAESSLER, Mylilus polymorphus fluruitilts 

 PALL., Mytilus Hagenii V. BAER, DESHAYES Conchyl. PI. 37, figs. 911, 

 &c. PALLAS first discovered this species in the Wolga; in Holland it was 

 first met with in the sea of Haarlem by H. W. WAARDENBURG, 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 

 BENEDEN 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 

 Baiae, an entire segment is seen, which is perforated by these animals, about 22 feet 

 above the surface of the sea; see POLI Test. utr. Sic. II. 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 

 LYELL Principles of Geology. 



