15 



email surface tubercles an- perforated or not 

 remains an open <|iie-tion, but I should I. 

 di.-posed to tliink that some of them, at any 

 rate, were M>. tnu- cnrn-spnndin:.' with "pott - 

 The ornate or expansions of thi- gpeciee <>tt< n 

 COTer Ian;.- surface- ; bur it i- certain that ir 

 iuaii_. a -real portion df the under fur 



face inu.-t have been free and unattaetn . 

 any foreign body. The _'< tu-ral thiekin SH of 

 crUBtfl varies from three to fuur line.- K 

 two inches or more ; but the latt. r specimen* 

 are to be regarded as bein_' cmpo-ed 



SUCee --ii.li of cril.-t- Hlpei impo-ed. tile V'UI 



U|.'in the older, as i- -hn\\n by the occurrence 

 of tubcreulated surfaces at variou- lc 

 throughout the ma-- 



l. -iiitii ui'ii JcniKition. Common, in a 

 siliciiied condition, in the C'ornifernu- lime 

 -tune of Ridgeway and Port Colborn- 



Fig. 2. a. Part <.f the under surface of a 1 

 specimen of Sfr<i,,/,it'ij,i,rn t>iti<r<-><tnt<i, slicwiiiL' the 

 wrinklnl la-. in. nt layer, am! the openings of th- 



oscula, natural size ; >>. a purtimi <.f the upper sur- , 



face, natural ^i/l ; c. a vertical section of a fi 

 ment of the -anie magiiitied to show the internal 

 tructure. 



3. STROMATOPORA PKRFORATA (Nicholson). 



>V t'orntu (Nicholson.) Annals and Magazine of Natural History. Jan. 



1874 



Fossil complied of cni-i- of varying' thickness, made up of thin concentricallv arran_ 

 ealcari-ous laminae, the interspaces between which are rendered vehicular by vertically dih 

 po-i-d ealean-ou- rod> k or dissepiments. From ibur to five lamina- with tlieir tnterrening iti- 

 terspaces, in a line. I'pper surl'.ie.- mi'lulatin-j-. and en\eri il with very nunien'U- ruiinded 

 apertures, which vary in width from twn thirds of a line to one line, and are pla.vd at di- 

 tances apart of a line, more or h Tin -< api-rtun-s arc usually ]! iced mi the summit or : t 



One side of ennieal emiii- r they are el.-vated .-ilmve the general surface, the lip of tl. 



niie_ r "n (.n.- -ide bciiu . m-rally lii'_ r her than on the tl,er These aperture- ; ,ri- the 

 fieei,f ni'in- nr !-- yertieal or .-.nni;wh:it <ihli ( |u<' canal- which penetrate tlie reticulated 

 r,f the ma--, and are line.l b\ a delicate ealcarecni- iie'inhrane marked \\ith faint 

 -tria K ict mril de-e.-nd- at fir-t and fur a eertain distance lahnut tliree lines) in a 

 urai-l.t line, , -md then i-cur\ rd -n WtO become nearly parallel i the lower sm faee ,,f the 111 

 it the ^ame true enntr 'i-tiir_' in it- diameter. |{etuee n the n-ciiln. a- jn-t d<- erihed the -ur 

 face i.- eii\en-d with a line miliary granulation, <. impu-ed nf minute pu-tiile-, phie. ". , 

 U'L'i'ther, and arranged in irre-iilar verinieul:ir aud -iniioii- \\n>'- 



perhaps, thi- nm-t remarkable -] eeie- nf the gentu ! 



ha-- hi . i, u \'t discovered; and it can nut In (Innbl. d tliat it IB a genuine im-mber df the 

 fill' ilmii.di in -nine re j.eei-. n aluinriiial (.in-. In its internal struetir 



'et h. r with x. 'ml S mammiUata ; and with the two Inrmer 



further in the- i n nf a --erie- n! aperture- which cannot he anvthm hir 



ilia." \ | however t IVC l"--n d. teeled. mile-- s.ilil' 1 "f'th, urlaci- t uhel. 



ild in reility b,- pi-rfnr-m.l whieli i- likel\ i-noii-_'h. 

 >'./'.//(./<// , 'in/iii-hed fr .111 \ tni h\ tln-mui-h ;-re ater nuinhei 



cln-er arrail-.'eiiieiit nf the n -eilhi. by llie e]e\alin|| of lln-e ( p. Tliir- - above 'I ' 



and dy the liner -rauulat im. nf tlic' u; p. r urlaee Tin- nuiiiber and < 



