92 PAL/EONTOLOGY 



Corbula (Trias.-Rec.) has already been described. My a 

 (Eoc.-Rec.) differs in being almost equivalve, and gaping 

 at both ends ; the anterior adductor is long and narrow, 

 and the pallial sinus deep. 



3. Adesmacea. Borers in stone or wood, with highly- 

 modified shell, in which the whole hinge-apparatus 

 becomes obsolete, while various accessory shelly struc- 

 tures are added to the valves until finally the latter form 

 an insignificant part of the skeleton. 



Pholas (Jur.-Rec.) has well-developed valves, though 

 they do not articulate, and is one of the few desmodonts 

 with radial ornament. The inner layer of the shell is 

 reflected over the hinge-line and covers the umbo ; there 

 is a curved rod projecting -from the interior of the umbo, 

 for the attachment of a pedal muscle, and accessory 

 plates on the outside in the region of the umbo. Teredo, 

 the "ship-worm " (Jur.-Rec.) bores in floating wood, and 

 has two small, short valves which are of little service 

 as a covering to the body, while the immensely long 

 siphons are encased in a calcareous tube. 



Short Bibliography. 



MOLLUSCA GENERALLY. 



COSSMANN, M., ET PsYROT, A. Conchologie Neoge- 

 nique de 1'Aquitaine, Soc. Linneene Bordeaux (1909-19). 



DESHAYES, G. P. Coquilles Fossiles des Environs de 

 Paris, 3 vols. (1824-37). 



FISCHER, P. Manuel de Conchyliologie (1880-87). 



NEWTON, R. B. British Oligocene and Eocene Mol- 

 lusca, Brit. Mus. Cat. (1891). 



WOODWARD, B. B. The Life of the Mollusca (1913). 



WOODWARD, S. P. Manual of the Mollusca (1851-56). 

 Still very useful, though much out of date in terminology 

 and classification. 



