ORDER III 



TELEODESMACEA 



421 



Family :v.). Cardiliidae. Dull. 



Shell cord if <>r in, ////// ///',,// /'/.-/// y(/-<,so,////-,,//s //.,//..<, ///////, ////'//, rm/i<i//i/ sculptured ; 

 r adductor *-<ir /m/>r> >-W ////</,/ // radial myoj>lir/r l<tinin<i, /// mit<-n'nr scar 

 tbngated, pallia! //// /// .</// ////./ .- ///.//,;./(/ i-.i-f ITU n I, seated on nymphs; rerilium 

 internal connecting j>n>jirtiiig chondrophorea ; hiti<i>' n-itlim/i ////.////>. /,/// ///, cardinal 

 teeth as in Mactra. Tertiary in KVcriil. 



Cardilia, De-lia\v>. Knct-ne ami 



Family 40. Mesodesmatidae. Deshaye-. 



,</<'// xr///(/ ///</ Jinn-if, iitinilli/ Dnilili-fftiriil, 



erect or opisthoyyrate beaks, otherwise as in the Mactridae; 

 siphons naked, not united. Tertiary to Recent. 



Mesodesma, Desh. Tertiary and Recent. JA/'- 

 , (Jonr. Eocene. Atactodea, Dall (Paphia, 

 J^rya;, Swains.) ; Davila, Gray ; Anapella, Dall. 

 Recent. Ervilia, Turton (Fig. 777). Tertiary and 

 Recent. Caecella, Gray. Recent, fluviatile. 



E. ASTHENODONTA. 



Fi.:. 777. 



<;i, Eicliw. Mi(iri-iic(8ar- 

 inatian Stage) ; Wiesen. in-ar Viuiuia. 1/1- 



Hinge often essentially Mactroid, but usually degenerate or obsolete, owing to modi- 

 fications induced by the burrowing habit. 



Superfamily 16. MYACEA. Menke (cm-end.) 



Burrowing, long siphoned, frequently inequivalve Pelecypods, usually with the taunt If 

 lobes largely united below, more or less united siphons, and degenerate hinge apparatus. 



Family 41. Myacidae. Woodward. 



Shell substance cellulo-crystalline, earthy, with a conspicuous ////>/<//,//.<. rn //-..-. un- 

 equal, more or Iras >'li></<ift>, rounded in front and gaping behind; adductor scars sub- 



equal; pallial /in' ."in nut,, I ; fill,// ma rgi it* 

 jiltn : urea obsolete or none: lnjn,,n,\\ ,i,nl 

 ri'xilium internal, opisthodetic, attached in flu' 

 left valve to a projecting chotukrophore merging 

 n-itli tin' <lnr*nl iinirgin behind, <nnl in tin 

 right valve to an inconspicuous, /'.>//-///// x///<- 

 umbonal chondrophore ; hinge edentnlun.< : 

 siphons united, with a horny tunic, not i<-]\Un 

 retractile. Tertiary and H-<vnt. 



o. 778. 



Myaarenaria, Lin. Pleistocene (Glacial Deposit.-^ ; 

 Hohusliin, Sweden. 



Linn. (Fig. 778). Snmnlli i-x- 

 Icrnally. Tertiary and Recent. 



Surface 



Sub - genera : Plalyodon, Conr. 

 decussated, siphon with horny 

 Cryptomya, Conr. Small, the pallial line discrepant in the two valves. N/<//"< -niu, Turtnii. 

 Minute, byssiferous, nestling. Tn<jnn-in, (!r;iy. Recent. 



Family 4-2. Corbulidae. Fleming. 



Shell small, much as in Mya, but the pallial line feebh' r nl^ntfte, the ligament 

 usually sub-external, separated from the resilium, which is hit IT no!, alivincular, o,nd 



