754 CLASS xn. 



to POLL The species are numerous, and the fossil, of which some corre- 

 spond to forms still living, belong principally, though not exclusively, to 

 the tertiary formations. 



Sp. Solen vagina L., POLI Test. utr. Sic. I. Tab. x. figs. 5, 6, BLAINV. 

 Malacol. PI. 79, fig. 2 ; in this species the hinge lies almost entirely at the 

 anterior end of the shell, and has only one tooth on each valve. In other 

 species it is situated further backward, always however nearer to the 

 anterior than to the posterior extremity of the shell; ex. gr. Solen legumen 

 L. from the Medit., Solen radiatus L., HUMPH. Amb. RariteitTc. Tab. 45, 

 fig. E, from the Indian Ocean, &c. 



Solemya LAM. (more correctly Solenomya MENKE, PHILIPPI). 

 Shell inequilateral, shorter posteriorly, rotundate at both extremi- 

 ties, covered with a periostracon, produced beyond the margins of 

 shell. Hinge callous, edentulous. Animal with trachea short, 

 branchia on each side single, plumose, formed of lanceolate lamellae, 

 disjoined, disposed in two series. Foot large, cylindrical, termi- 

 nated by a disciform expansion, fimbriated at the margin. 



Sp. Solenomya mediterranea, Tellina togata POLI, I. Tab. 15, fig. 20, DESH. 

 Conchyl. PI. 3, figs. 1 5 1 7. The animal is figured by DELLE CHIAJE 

 Memorie sulla storia e Notom. degli Anim. s. v. Tab. 62, figs. 10, n, PHI- 

 LIPPI in WIEGMANN Archiv fur NaturgescJi. 1835, Taf. iv. s. 171 276, 

 and DESHAYES in Cuv. R. Ani., ed. ill., Moll. PI. 115. Comp. also 

 DESHATES Encycl. metk., Vers. in. pp. 956, 957. Solen australis LAM., 

 BLAINV. Malac. PI. 79, fig. i. 



Family XXII. Pholadacea. Mantle sacciform, open ante- 

 riorly, with a fissure emitting the truncated foot. Two fistulous 

 tracheae, very long, conjoined in most, contained in a common 

 covering. Branchia3 elongate, free at the apex, produced within 

 the tracheae. Shell at each end gaping, with no ligament, a 

 styliform or spoon-shaped process at the hinge in each valve 

 advancing into the cavity of shell. 



Pholas L. Shell inequilateral, elongate posteriorly, thin, equi- 

 valve. External accessory calcareous parts at the hinge. Animal 

 (Hypogcea POLT) with foot short, thick, its disciform apex flat or 

 excavated. Two long trachese conjoined. 



Stone-borers (0w\c$ from 0wX^ai, to lie hid in a hole); some of these 

 animals live at the bottom of the sea near the strand; others penetrate 

 very hard rocks, madrepores, corals, &c. From the opening at the hinder 

 end of the shell turned upwards proceed the two connected tubes into 

 which the mantle is prolonged. The mantle is thrown over the hinge, and 

 contains small supernumerary pieces of shell of various form in the different 



