2!M) 



The zoarinm consists of a narrow, bifoliate. hraiKliin;; fn.ii<i <>i- ( rilir«isc 

 forms, with a pointed Itase, articnlatinfi witli a small liasal cxpaiision : 

 aportures subcirt'ular, surrdinidcil liy a pci'islonic siihp(ily,i.'<.iial in oiil- 

 lino; interspaces depressed, usually wilh (Uic or two line lortuous clcvatci! 

 linos. 



(Irnptodicti/a fruticoHd ii. .s/*. I'late XII. Kii^s. 1-2. /((ariuiii <(insisls of 

 bifoliate brandling frond. 1 to 1..". mm. widi'. The branches rise' iieipendic 

 ularly from the margins and are irrcRUIarly spaced from one another, (in 

 the type specimen tlie distance between the branches vaiies from .1 mm. 

 to 1.5 mm. and portions of the zoarium can be seledeil in wliicb 4 stipes 

 spring from one margin and one from the opposite mai-gin in the sjiace of 

 5 mm. Some of the brandies develop ;ind bifurcate similar to the jirineipal 

 stipe and others form short lateral extensicais 1 to ."! mm. in length. The 

 bushy effect resulting from the Irregular branching was observed in a 

 number of siiecimens. with similar internal characters, and is here consid- 

 ered of specific value. 



Sections show that the apertures are oval, arranged in longitudinal series 

 and separated by two fine tortuous lines. Fine zooecia occur in 2 mm. within 

 the series. At the bifurcation, the striated api)earjince is increased by 

 the presence of narrower apertures; the serial arrangement is less definite, 

 and the fine tortuous lines occasionally wind diagonally jimong the zooecia. 



The primitive tubes are thin-walled and lie upon the median laminae 

 from the proximal end to the hemi.septum. where the outward turn is short 

 and sufficient to permit the tube to approach the sui-face perpen<li(Milarly. 

 Diaphragms, mesopores and median tnbuli are wanting. 

 The hemisepta is short, blunt, and pi-ojects directly towards the nieso- 

 theca. 



The form of the zoarium distinguishes this species from others of the 

 genus. 



Occurrence: Pierce limestone, Walter Hill. Rutherford County. Tennessee. 

 Holotype : 237-12. Indiana University. 



Graptodictyn (Icndroidru n. sp. Plate XII, Figs. 3-4. The zoarium forms 

 a narrow liifoliate frond, l.o to 2 mm. wide. The first. 10 to 15 mm. above 

 the articulated base, is an luibranched stipe above which dichotomons 

 blanching occurs every 2.5 lo .'! mm. 



The zooecia are oval, arranged in longitudinal rows, s to ;> in 2 mm. 

 Two tine lines separate the rows in the middle of the hileral sniface. but 

 near the border where the long axes of the apertures are obli(iuely directed 

 the tortuous lines pass between the apertures in the .series. The walls of 

 the zooecia in G. fruiicom are thinner, the ai)ertures larger and the longi- 

 tudinal rows (14 to 14.5 in 2 mm.) more closely crowded than in (1. 

 d'cndroidca (13 to 13.5 in 2 mm.). 



The form of the zoarium of G dcndroidca is characteristically different 

 from all other described species. 



Occurrence : Pierce limestone ; Walter Hill, Rutherford County. Ten- 

 nessee. 



Holotype: 237—13. 14. Indiana Finversity. 



