484 



MOLLUSCA 



PHYLUM VI 



tlie divided adductor scar of the lower valve. Behind the anterior there are two 



supplemental processes, which are received into the 

 sockets d' and d" of the lower valve. The species are 

 aliundant in the Middle and Upper Cretaceous, and occur 

 chiefly in littoral sliallow water deposits. The most 

 noted localities are the Alps and Pyrenees, Provence, 

 Charente, Istria, Dalmatia, Greece, Sicily, Asia Minor, 



Persia and Algiers. 



Barrettia 

 Guatemala. 



Woodward. Cretaceous ; Jamaica and 



Superfamily 7. LUCINACEA Anton (emend.). 



Fir YSti 



^ ,,^ Shell v-ith. the anterior adductor scar narrower, 'pro- 



Hippuntes cornu-vaccinumGolai. , , , 77 • 7 



Ui)perCretaceous;G()san, Austria, duced ventrally ; imsterior scar sliorter, rounded; imuiab 



Srsho:'inru.e"int?;;ocS U^^^ si^nple; M ehngcUe, sub-dacate ; hincje feehle, teeth 

 ciithruiu and rt-iation of tho slieii- radial, often obsolete. 

 layers. 1/2 



Fio. 7S8. 



Tancredia {I'alaco- 

 mya) coraUina Zitt. 

 Ta?icr('f?i(is«'Kri/o/-7HJs (Danker), Lower Lias ; and Goub. Coral- 

 Hettingen, Lorraine. 1/1 (after Terqneni). Rag ; Glos, Calvados. 



Fi(i. 



Family 15. Tancrediidae Fischer. 



Shell donaciform, equivalve, with an external lirjament ; the margin of the valves 

 entire; hinge with posterior 

 and anterior laterals, the latter 

 inconstant ; cardinals one in 

 the left and two in the right 

 valve, or two in each valve. 

 Trias to Cretaceous, (?) Eecent. 



Tancredia Lycett (Het- 

 tangia Terq.; Palaeomya Zitt. 

 and Gouh.) (Figs. 787, 788). 

 Shell sub -arcuate, attenuated 

 before the beaks, wider and 

 shorter behind them ; obli- 

 quely truncate and somewhat 



o-aping posteriorly ; a cardinal tooth on eacli side, and also an elongated posterior 

 lateral. Trias to Cretaceous ; maximum in Lias. 



(?) Meekia Gablj. Cretaceous ; California. (?) Hemidonax Mcirch {Donacicardium 

 Vest). Recent. 



Family 16. Unicardiidae Fischer. 



Shell cord.iforni, equivalve, closed, concentrically striated; adductor scars cUi'ptical, 



the anterior longer ; fallial line simple ; margin of the 

 valve smooth ; ligament external, parivincular, seated in a 

 groove ; with a grooved hinge-plate bearing a single obsolete 

 cardinal in each valve, or none. Carboniferous to Cre- 

 taceous. 



Unicardium d'Orl). (Fig. 789). Rounded, inflated, 

 with incurved l)eaks ; hinge margin thin, with a weak 

 cardinal tooth ; ligament deep seated. Trias to Cretaceous. 



Scaldia Ryckholt. Carboniferous. 



Pscudedmondia Fischer. Ligament completely external. 



Fio. -8i". 

 Unicardium cxceiitricum d'Orb. 



Kiranieridgian ; Cap de la Heve, ( ^,.l,miifeTous 

 near Havre. Vi- UailJOniieiOUS. 



