PLATE XXVIII-Continue.!. 



StIOTOPOKA FKUTIC08A. 



Pngc M. 

 Pi(r. 12. A specimen, natiirnl size, showin)f tl;ie mpd^ of br^pchinp ami arrang-einent of cell apertures. 

 Fig'. 13. An enlnrfronient from a jwrtion of fijf. 12, the surface being- well preserved, sliowing the form and 

 - .-jiun ui  arrautrement of cell ape«.>toi'ee«.4iMl>4be oi-namentatMn of lUtftinliencfUulM'Bpace and.of the non* 



:. eellulifei-ous margin. i' , .ill r. -■:' , n..i,fi.»| i,r»U,<irrn .iii t  •,:'■>„: 



Figf. 14. An enlarg<>meMt from a portion of fijf. 13, the siirfiuie being- much weathei-ed. The cell apertures 

 are larg-er than tho.'ie of fijf. 13, and ap|)ai-<'nlly more irrejfuhii'ly arranged. The ornamenta- 

 tion of the surfacre is nearly or quite obBoleta. ,, iifT>ixoA 

 Upper Helderl)erg group. NfW Y>frk. 



'.id 1o »Ij<y '■ f)rfi viiit«..i(- r. )o Mia Imutan 9tlT .& .■ji^ 



StIOTOPORA BIGIDA. .,,j,.,i,i^Hi».iqU 

 Page 91. 

 Rg. 15. A specimen, natural size, showing the rigid form and mo<Je of branching. 



Pig. 16. A jwrtion of fig. IB, enlarged, showing the form ami arrangement of cell apertures, the striated 

 longitudinal ridges and the non-colhiliferous margin. (X 6.) . , , ,. ,_. 



. .ygper Hdfippberj^ group. Near Le Roy. N. T. 



 StifOTOPORA 8BMI8TRIATA. 



Page 05. 

 Fig. 17. A specimen, natural size, regularly bifui-cating. 

 Fig. 18. A specimen, natural size having lateral branches. 

 Pig. 19. A portion of a specimen enlarged, showing (he form and aiTangement of cell apertures, and 



-•t'Klii li'., strong longitudinal lidges. (X 6.) ' I'l !■ < - '! 



Fig. 20. An enlargement of a portion of another specimen, on which the cell apertures are apparently 

 ''■' " moi-e irregularly aiTanged, and the longitudinal stiiations are obsolete. '';'■' 



Il«) I*!"*""'!'"!.,, .- pj,pg,. jjg,^g,.,,g,.g ^,.„„p Near U Roy, N. T-- "' yn^/i^i ,/J'w« mow 



,».nv- 



Stictopora Gilberti.^''*'"'*''''^ ■•*»'«" 



Page 90. 

 .5fJAlH.H>]gee Plat^ ».i'HT//.0 A 



Fig. 21. A specimen, natural size, showing the form and mode of branching. , 



Piff. 22. An enlargement of a portion of fig. 21, showing more plainly the mode of bifurcknbn, tne'hon-c^F. 



luliferous margins, the form and arrangement of cell apertures, and the longitudinal striations 



or ridges. (X 6.) 



Upper Helderberg grtiup. Phils of theOhio river. 



Stictopora ovatipoba. 



Pago 93. 

 See Plate 27. 



Fig. 23. A specimen, natural size, showing the form and mode of gi-owth near the base. 

 Pig. 23a. An enlargement of fig. 23, showing tte base, mode of branching, non-celluliferous margin, form 

 and arrangement of cell apertm-es, and the strong longitudinal ridges. (X 6.) j 



Upper Helderberg group. Palls of the Ohio river. 



Stictopora invebtis. 



,, , ;, P»ge,9^,,.,, ^ /r 



Fig. 24. A specimen, natural size, showing the form and mode of branching. 



Fig. 25. An enlargement of a portion of fig. 24, showing the non-celluliferous margin, and the form and 

 arrangement of the cell apertures. . ^ 



96. A vertical section from Sg. 24, showing the mesiAl septum and the form and manner' of grdWth 

 of the cell tubes.  



Upper Helderberg group. New York, l'"*"'^ S''"" "1 



%• 



