CONTEN IS 
JjIST of Plates... 
Letter of Tran.smittal, by E. F. Pitt.man, A.Pi.S.M., Covernmfnt (iEolo(;ist 
Fnder Secretary for ]\Iixf,s 
Preface... 
MEMOIIi. 
T. — Introductio.n 
PI. — Descriftiox of T7IE Genera axi) Species ... 
Class — Pelecypoda ... 
Order — Prioxodesmacea 
Sectiox — Tsodonta 
Fa M I LY AviCU LO PECTI X I DyE 
Gexus — Aviculopectex 
,, Deltopectex ... 
Family — Pectixid.e. . . 
Genus- Extolu m 
in — T able of Distributiox ... 
TV. — Plates and Explanations. 
