Palaeontologie. — Crj-ptogamen im Allgemeinen. 491 



Weiss, F. E., A Stigmaria with Centripetal Wood. (Ann. of 

 Bot. Vol. XXII. p. 221—230. with a double plate. 1908.) 



The author describes the first English petrifactions of Stigrnaria 

 with centripetal wood. They were obtained from the well-known 

 Hard Beds of Halifax in Yorkshire (Upper Carboniferous). 



The central vascular cylinder is small, measuring onl}' 75 cm., 

 in diameter, and, in transverse section, might well be mistaken for 

 a Lepidodendron twig. Of the outer tissues the periderm, consisting 

 of 6—8 rows of thin-walled, rectangular cells, is alone preserved. 

 This is ver}^ similar to that of a typical Stigrnaria, such as S. ßcoides 

 The periderm has a verj^ extensive circumference. Rootlet cushions 

 are present, but no roots occur in continuity with the specimen. The 

 secondary wood is fairly well preserved, and of normal type. The 

 centripetal primary wood consists of small protoxylem elements on 

 the outside, followed on the inside by a metaxylem, consisting of 

 about two rows of tracheids, the innermost of wich are of very 

 large dimensions. The protoxj^lem elements are offen Spiral or an- 

 nular, the metaxylem are large scalariform tracheids. Within the 

 metaxylem a parenchymatous pith occurs. 



This Stigrnaria is distinguished from 5. ßcoides by the absence 

 of the ver}'' broad medullary rays which break up the woody cylin- 

 der into distinct wedges, and in which the rootlet bundles pass out 

 to ' the exterior. 



The course of the rootlet bundles is traced and is found to be 

 oblique, and to this is due the fact that the central cylinder is not 

 split up in the manner usual in Stigmaria ßcoides. 



The author concludes that this specimen is a Stigmarian axis, 

 and not the stem of Lepidodendron miindum as Williamson supposed , 

 on the following grounds. The wide periderm, its peculiar structure. 

 and the presence of remains of rootlet cushions are in favour of 

 Stigmaria rather than Lepidodendroji. The absence of the primär}' 

 outer cortex of hard texture distinguishes it from the stem of Lepi- 

 dodendro)! mioidum. In the curious, centrical lateral bundles, and 

 the System of delicate reticulate cells, this axis agrees more closely 

 with Stigmaria Briardi Renault, than with any Lepidodendron stem. 

 Further points of agreement may be found in the origin and course 

 of the lateral bundles. 



The author concludes that this Stigmaria ma}'' well belong to 

 BotJirodendron , of which the leaf-bearing axis has been described 

 under the name Lepidodendron niimdnm , although only one case 

 has yet been found in which the latter shows secondary thickening. 



Arber (Cambridge). 



Migula,W., Kryptogamenflora. Moose, Algen, Flechten und 

 Pilze. (In Dr. Thome's Flora von Deutschland, Oester- 

 reich und der Schweiz). Lieferung 49 — 53. (Verlag von 

 Friedrich von Zezschwitz, Gera in Reuss j. L. 1908. p. 1 — 144. 

 Mit 25 zum Teile färbigen Tafeln.) 



Diese Lieferungen, den Beginn des 2. Teiles des IL Algenban- 

 des vorstellend, befassen sich mit den Rhodophyceen und zwar mit 

 den ganzen Bangiales und den Florideen\ innerhalb der letzteren 

 Unterordnung werden die Reihen der Nemalionales, Gigartinales 

 und der Rhodymeniales im Ganzen behandelt, die letzte (die vierte) 

 der Cryptonemiales liegt noch nicht abgeschlossen vor. Auf p. 12 

 fehlt im Schlüssel der Reihen der Name „Cryptonemiales''. Der 



