48 



Pirtm (Ps,utla>ini»stiim) plica Liiuir. PI. VII, f. 'M. 



(Syst. imt. cd. 12, |.. II4r).-S«.wfrl»y. Tins. vol. I, p. C), pi. 20, f. '2:17 

 — -J^'.». — Rctvi-. Couch. Icon. Pit-tfii, j.l. !<. 1". 1<">. l.isclikc Japiii. 

 JiitifS-Coiich. vol. 2, p. l()0, vol. :\, p. II :m. 



Tills ra<li;i!ly ribbnl iiiitl i.lr<iii;j;ly fukU-J «[«.ciits is tin- most In-ipu'nt ol nil 

 llie IVctiiios of Oji. 



I'icteii. (Volii ) lui/matii» Sowiiliy I'l Vll, 1". :>l ami .'51 a 

 ('J'licsinriis Udiieli. vol. I. )>. 4(1. pi. 1.'). f. lOl.— lUcv, Coiidi. Iron. 

 ruLltM), pi. :J0, r. 13.').— Lisildti-, Japm. Mtrm^-Coiiili. vol 1. p H'>7. 

 vol. 2, ).. I.")?, pi. 12, r. 1 aii.l 2.). 



Nt.iily circular willi alxnil |;5 broail anil rL<'tanj;iil ir lil*. l>roa 1<t lliaii tliv 

 interv.il^ in tlio convvx v.vlvr. sni iIKt in the Hat one. witli foncintriial stria-, Ihi« 

 slit'll— tliinmr tlian tlie allied s|K.-ci<'s <;«'n«Midly arf-is fonnd rarely at OjI. 

 Jloix- iiinnurons and a littles lari;c'r s|Kviincns will In- nunlionod from ^^^linagllWrt. 



JWli:ii (Void ) Yesgoi-iiiiiK .Tay. 



(K.port. on the shells coll. hy l'c'rry's Exped , p. 211:). p!. 4, f. 1 and 2, 

 jil. :?, f. :}and 4.— Diinker. Novit. Uf.ndi. p. CI, pi. 2J.— Jxhremk. -Moll, 

 des Aninrlandes n. nordjapm. Meeres, p. 4"^ k |>U 20, f. 1-4.— l.isehke. 

 I.apan Mcens-( :on«li. vol. 1. p. jC.'i. pi. lo, f. :5S4, vol 2, p. l.")7, |il. 

 K?.). 



Many ronnded and not very laoad radi.ilinjj rihs cover the »nrfu-e of the 

 shell. They arc not radially striated, Init sliow oidy the lines of >;ro\vlh. The 

 sha<j;reen like epidermis of the Hat valve, s«'en in all tin' rect'nt spn irnens from 

 Hakodate, ;ire not pre.'erved in the fossil speeiniens. which do not ^llow neitlier 

 the overlappin;; of the con«ivu valve, and, on the whole, arc not at all frequent. 

 l''spe<i,illy from Oji I have <;•'' ""dy fnij^menl,-*, snHieient however to ^ive donlit- 

 less evidence of the presc;nee of this sjK'cies in the tertiary layein of the enviroUK 



i.fT..k;.. 



I'fii.a <li>l>ts ThnidK-Pfj. 



( Konj;. Vet^-nskaps ukademiens nya handlinRur. vol. 14, 17!IU, p. 14". p|. 

 <>, f. I-I).— Lisehke .lapiii. Meeres ('onch. vol. I, p. 174, vol. 2. pi. 14, f. 

 1N2, p. Kit), vol. .3 p. 114. — Syn. 0. Ij\|itroiisii Schri nek, Nord jap. Moll. 

 1>. 47.0. pi. 1!», f. l-(i. anit. I.ischkel. 



Like liischke, I eonfmc myself to identity the shell which 'in the fossil 

 stall' li;i.« In-en met with at Oji and in most of the lo^'ulitii-s to lie nientionc«! in 

 the follovvin;; chapter« somewhat more rarely thiin it is now fonnd. It is 

 eminently elon;;aled, has a stron<r shell. somew'h,it laminated, |>fiinle<l in tlie lower 

 va've. the npi»c-r King shorter and flat. 



