104 MIOCENE FAUNA. 



same habits as at present. The Molassic sea possessed repre- 

 sentatives of all these families, and some of the species are still 

 living. Near St. Gall Saxicava arctica, Linn., has formed in 

 the rocks pear-shaped holes precisely similar to those made by 

 its descendants, which now live on all northern coasts and also 

 in the Mediterranean. A large Panopaa (P. Menardi, Desh.) 

 forms great shell-beds on the Langenberg near Berne, and is 

 found near Eriz, Lucerne, and St. Gall. It indicates shallow 

 water, and it probably buried itself in the sand of the shore like 

 its living relative. Of the Pholadida two species (Pholas cylin- 

 drica, Sow., and P. rugosa, Broc.) are common in the Molasse ; 

 the second lived in holes which it bored into the rock. 



Ship-worms, which have sometimes caused so much injury by 

 the destruction of wooden vessels in sea-ports, also inhabited the 

 Molassic sea ; fragments of wood are frequently met with tra- 

 versed by tubes perfectly identical with those now formed by 

 the common ship-worm (Teredo norvegica, Spengl.). As this 

 species has been found in Italy in more recent deposits, it is 

 hardly to be doubted that it has continued from the Tertiary 

 epoch to the present day, and has constantly inhabited this 

 region. 



The Clavagellida are represented by four Clavagella and 

 Gastrochena, which bored into various substances. The Solen- 

 acea (or razorshells) , deriving their name (solen, a water-pipe) 

 from the form of their long narrow shells gaping at the two ends, 

 are still more numerous. They present several genera (Solen, 

 Psammosolen, Ensis, and Polio) , including species which are for 

 the most part still living in Europe ; these animals dig perpen- 

 dicular holes in the sand to a depth of 2 or 3 feet. The Litho- 

 phagae bored into stones; and one species (Petricola lithophaga, 

 Retz.) is not unfrequently met with in rolled fragments of lime- 

 stone. All these animals are characteristic of the sea-coast ; and 

 the holes bored by them into the rocks enable us to recognize 

 the ancient shore and the level of the water upon it, even when 

 the animals themselves have entirely disappeared. 



The Mollusca constitute the principal part of the fossils of the 

 marine Molasse. The Polythalamia, which occur elsewhere in 

 great quantities in contemporaneous formations (for example, in 

 the Vienna basin) , have not as yet been investigated. Of corals 



