TERES RATULIDjE. 309 



10-120 fathoms. Fossil, 22 sp. Jurassic — ; United States, 

 Europe. T. caput-serpentis^ Linn, (cxxxiv, 14-16). 



Shell finel}' diehotomously striated, auriculate, deltidium 

 usually rudimental ; foramen" incomplete ; loop short, rendered 

 annular in the adult by the union of the oral processes. 



Waldheimia, King, 1849, 



Syn. — Magellania, Baylo, 1880. 



Distr. — 9 sp. Norway, W. Indies, Java, Australia, California, 

 Cape Horn ; low-water-^100 fathoms. Fossil, 90 sp. Carb. — ; 

 South America, Europe. W. Australis, Quoy (cxxxiv, 1, 17-19). 

 W. Jlave.^cens, Lam. (cxxxiv, 20-22). 



Shell smooth or plaited, dorsal valve frequently impressed ; 

 foramen complete ; loop elongated and reflected ; septum of 

 smaller valve elongated. 



WALDHEIMIA (restricted), Dall, 1871. Shell globose, neural 

 beak more or less produced ; foramen complete or incomplete ; 

 deltidia separated or united ; pedunculated ; a ridge or septum 

 usually existing in the haemal valve. Mouth behind the brachia, 

 which consist of two lateral lobes and a central spiral lobe. 

 W.Jiaveiicens, Lam. 



EUDESiA, King, 1850. Shell swollen, oval; valves sharply 

 plaited ; beak-opening round, large ; median septum and tooth- 

 plates developed. W. Grayi, Davidson, and 6 fossil sp. 



MACANDREVIA, King, 1859. (? Gwynia, King, 1859. Neothyris 

 and Plesiothyris, Douville, 1879.) Smooth, longitudinally oval, 

 inequivalve, the condyle valve being the largest ; foramen emar- 

 ginated by the deltidial fissure ; umbonal cavity of large valve 

 furnished with two muscular fulcral plates passing somewhat 

 perpendicularl}' from the dental protuberances to the surface of 

 the- valve ; umbonal cavity of opposite valve also furnished with 

 similarly directed plates ; cardinal muscular fulcrum excavated 

 in the substance of the hinge ; loop long, strongly recurved, and 

 extending in front of the centre of the valve. Includes the 

 recent W. cranium, MiilL, which is the type, and a number of 

 fossil forms. 



ZEiLLERiA, Bayle, 1879, (Macandrewia, Schloen. Orthotoma, 

 Quenst., 1871.) Differs from Waldheimia in the presence of two 

 rostral partitions upon the hinge. Jurassic — Tertiary; Europe. 

 W. lagenalis, Schloth. (cxxxiv, 23). 



AULACOTHYRis, Douville, 1879. Apophyses, rostral partitions 

 and septum as in Zeilleria ; foramen generally small and oblong. 

 Distinguished by its exterior form, the smaller valve having a 

 median furrow. Triassic, Jurassic, Cretaceous. W. resupinata, 

 Sowb. (cxxxv, 24). 



ANTiPTYCHiNA, Zittcl, 1880. Large valve swollen in the middle, 

 with a strong fold on either side ; small valve usually somewhat 



