PALEOBOTANY BERRY. 327 



branched. Bolsters are usually wanting and the leaf scars are re- 

 mote, small and circular or rhomboidal, they show a central leaf 

 trace scar and two lateral parichnos scars; immediately above and 

 close to the leaf scar is a small ligular pit. The leaves were small, 

 linear lanceolate, univeined, and more or less persistent. In one species 

 (B. jmnctatum) the self-pruning of branches resulted in the large 

 scarred impressions known as Ulodendron. The term Rhytidoden- 

 dron has been used for some species and recently the genus Poroden- 

 dron has been proposed for certain forms from the Lower Carbonif- 

 erous of Russia and Spitzbergen that were formerly referred to 

 Bothrodendron. Anatomically, the stems show either a small pith 

 or a solid core of wood with external protoxylem. The secondary 

 zone of wood was thin and the cortex was less differentiated than in 

 the Lepidodendrales. 



A cone, Lepidostrohus Olryi Zeiller, which is considered to have 

 belonged to Bothrodendron minuti folium is of the usual Lepidostro- 

 bus type with elongated sporangia. A small cone with a histology 

 that suggests its having been borne by Bothrodendron mumdum lacks 

 the radially elongated sporangia and instead has them extended 

 upward inside the sharply flexed bracts and is conspicuously ligu- 

 late. It bore microsporangia in the distal and megasporangia in the 

 proximal region. Another type of cone, Lepidostrobus Zeilleri, 



Explanation for Fig. 12. 



A. Lepidoearpon lomaxi Scott: 



1. tangential section (after Scott). 



2. diagram of sporophyll; m, micropyle, St. stele (after Seward). 



3. tangential section near distal end of immature sporophyll; 1, ligule (after Scott). 



B. Miadesmia membranacea (modified from Scott): 



1. tangential section la and b, lamina of bract forming wings; v, velum or integument with its processes; 



e, sporangium. 



2. radial median section m, micropyle, 1, ligule. 



C. Pinakodendron ohinann, megasporangiate sporophyll (after Kidston). 



D. Spencerites insignis (after Williamson): 



1. spore showing wing in surface view, sp. cavity, w, wings. 



2. tetrad in section showing 3 spores. 



E. Mazocarpon. Diagrammatical transverse section of megasporophy 11 (after Benson). 



F. Lepidostrobus veltheimianus, median vertical section. 



G. Same showing megaspore, M, and microspore, m, in section (after Kidston): 



2. single megaspore in surface view. 

 H. Cantheliophorus, 1, radial and 2, transverse section (after Bassler): 



a, axis; b, blade; c, pedicle; d, sporangium; e, brace; f, crest; g, keel; h, guard. 

 K. Bothrostrobus, median vertical section (after Watson). 

 L. Sigillaria spinulosa (after Renault): 



1. leaf from below showing furrows and scar. 



2. tangential section of outer cortex showing leaf trace and parachnoi; 



pa, parachnoi; x, xylem, primary above^ secondary below; tr, phloem; s, sheath of bundle. 

 M. Sigillaria latifolia, transverse section of leaf (after Renault ) : 



x, xylem; s, schlerenchyma; tr, transfusion tissue; g, stomatiferous furrows. 

 N. Lepidodendron bolster. 1, surface view; and 2, in median radial section: • 



a, ligule; b, leaf and leaf scar; c, leaf trace; e, parachnoi. 

 O. Sigillaria bolster in surface view: 



a, ligule; b, leaf scar; c, leaf trace; e, parachnoi. 

 P. Spencerites insignis, Diagrammatical radial section showing two sporophylls with megasporangia 



(after Berridge). 



