4 E. BlUmija — Nero Specks of StricklanJinia, 



beooincB obsolete m\h \\3,e. ; fowanlR tlio fmiit this Hinin often Jgivew pla^e to n well- 

 (li'\('lt.|H'(lfnl(l. S.iine iif the liirt^i: iinliviilnal.^ lirivH imitticT fi l(i nor hiiiun in this 

 vahu. Tiic dorsal vuIvh u.siiiilly cxJuhits n f'olil, whirl, bcainuH ;^ra(luiill\ hro;iiicr 

 tioni thfc l)o;tk tf) the trurit, \vh(:rf its wiiltli w equal ti' tli.it oi tltti l'>n(;uc-like 

 |ii()ieetiiiu. Iti'.' (uiihfines und bi iiks* uro so slightly developed u-^ to ^ive only u very 

 moiierati anpiidation to tlic eardinul extremity. I'ho bia^c-line is ihoiit one-third 

 or one-t'oiirth ol the wljolt; width, and thti areas are, in general, eoin.cakd by tho 

 (hise apiiiOKirnatiini id the beaks \\\hm the valve-^ are i?i plai.v'; but in sepaiated 

 valve* the vonlr.tl area is will t-een that ol "lie dursa] \ah' is linear. In the 

 intorioi- of tho ventral valvo tho mesial septum extends only (<;ur linen tVem ttin ii< ak 

 in a ijieeimen thirtv lines in lonjr'h ; tic lii.ingu! ir ehainher it :ip]>a;(.ntly two lines 

 in length. In tie' dorsal valve tin; socket plates an. very .short, and not united . ihty 

 have, as yet, only bei ii -een bv !,'rin(linj^ (Town the beak. The small hpe<.iRiens are 

 smooth, or only exhibit faint in<)ications t f ribs ; bnt as tho shell iiiere-ases in size 

 the ribs bedirm,- stronger, dth.ajgb in i-omc of ti e larger (a.-in tiie one tigiired) they 

 are not very ili-tinet. In iriniral theie are throe i»r four ribs runninii.': stiaitrbt from 

 the beak to the t'rort ; but on eaeh side ot these thev (airve outwaids to ihe sides, 

 Tho ribs are rounded, ami there are from throe to live in tlie width of three liiu;s .it 

 tin; maiBfin. There are also fine coneentrie wrinkles, not, howive'r. alway- visible. 



Lengtli of largo indi\idu.'Us, three inches; widtii. vuyini,' iroui neaih e((Ual to 

 one-tit>Ii los.s than the lengtli. They occur c '^ all sizes fiom a length of three- 

 frurths of an wvh to three inches. 



068. — StricldaiiiUnia Davidioiiii (lifior^j from S. leas, in being :n »re 

 naiTowod in front, iiioro stvoiiglj' rildiod, ouil in luiviii^ tho area 

 conoe.-ilc'il vshen the two valves are in their aatiiriil |.iosition. N<'t- 

 witlistiindiufi; the variahhi form of tlie shell, tlKn't! are none, in a 

 ciilliicti"n of nearly a. huudrotl speeiinens, that c(in]d be eoti»jidered 

 H{H'(ifie;;dly identical witli any oi those t.'.f;'m-<:'d hy Mr. T>u>'\dsoii in 

 the " Moiie>gvaph."' pi. xix, lij>-s. ] 1-21. Hut thtMV is a dorsal A'alve 

 from the \i!i>j,ara limestont^ of Cabot's Head, [-ako Ilnron, exeeedingly 

 like fig. 13. It i.s, however, quite distinct fioui S. Davkhonii, and I 

 think from iS. h'us also, 



A.s before stated the large individuals often have tho ribs strongly 

 d'^\eloped, and curved out to the sielevs. They thus closely resemble 

 the figure of S. llrnto in " Sil. Syst.," ph xxii. tig. (>. Indeed I 

 could very nearly re-produce that figure from some of our broken 

 .speeinKms. It i^! these that I thought couJd be identified with 

 S. lirata. Tho smnll smooth ones I supposed to bo .S', h-ns ; hut, 

 after seeing Mr. .r'avidson's figures, I r(^-e.\iniuned the wliole col- 

 lection, and found that thei'O is a gradual passage from tho smootli 

 to the strongly ribbed. The specimen figmvHl ffigs. 1-1 r) is ;ibout 

 as perfect as a fossil can be, arid is a good esamplo of an intermodiatt' 

 form. 



Position and lotaltty. — lliis species occurs at a number of locaHties 

 nround the coast of the Island of Anticosti, from Jupiter river to 

 Eiist I*oint. It is most aliundant at South-west Point, where the 

 spiH.imen figured was collected. It is associated vith Styophomenn 

 rhomhoidalis, S. perten, S. antiqaata, Lej^tama trmisrersnliH. Orihif> 

 Dniidsont, Pentan. -us oblonyus, Spiri/era pUcatd/a, heptocmlia 

 (Atrypa) hemispherica, Atrypa reticularis, and many ethers, mostly 

 new species. Tiio rocks belong to the Anticosti group, division 3, 

 a horizon which is very nearly, if not exactly, that of the Upper 

 Llandovery rocks. It also abounds on the mainland at the Schick- 



