Mr. R. Kidston on TJlodendron. 123 



The rostrum is distinctly longitudinally impressed, tlie im- 

 pression bordered on each side by an obtuse ridge. The disc 

 of the thorax has a short but distinct ridge. The elytra are 

 obovate, more strongly striated than in E. gracilipes, the stria3 

 strongly punctured ; the scales on the interstices long and 

 narrow, but not hair-like as in E. gracilipes. 



This species has the shoulders of the elytra bounded by a 

 distinct ridge as in E. brevts, but that is a short and broad 

 insect. 



These specimens having been in alcohol it is probable that 

 the paucity of scales may be due to abrasion. 



XVI. — On the Relationship of TJlodendron, Lindley and 

 Hutton^ to Lepidodendron, Sternberg -^ Bothrodendron, Lind- 

 ley and Hutton ; Sigillaria, Brongniart ; and Rhytidoden- 

 dron, Boulay. By E-obeet Kidston, F.G.S. 



[Plates IIL-VII.] 



At the meeting of the Royal Physical Society of Edinburgh, 

 held on 21st March, 1883 *, I exhibited several specimens of 

 the so-called genus TJlodendron, Lindley and Hutton. I then 

 stated that I did not regard TJlodendron as forming a true 

 genus, nor as entirely belonging to Lepidodendron, as some 

 authors seemed to suppose ; but that the genus, as usually 

 employed by those who believe in its individuality, includes 

 plants belonging to the genera Lepidodendron^ Sigillaria^ and 

 Rhytidodendron'\ . 



Almost all the misconceptions on the true affinities of TJlo- 

 dendron have arisen through the neglect of a very essential 

 element for the right understanding of these fossils, and one 

 which only requires to be mentioned to be fully agreed in 

 by all botanists, viz. that only well-preserved examples should 

 be taken into consideration when critically considering the 

 affinities of this genus ; unfortunately this has not always 

 been observed. 



When determining the various species of the genera Lepi- 

 dodendron and Sigillaria, unless the outer surface of the bark 

 is well preserved and exhibits the form and arrangement of 

 the leaf-scars, it is admitted that the plants do not show the 



* Proc. Royal Phys. Soc. Edin. vol. vii. p. 356 (1883). 

 t Boulay, ' Le terr. houil. du nord de la France et ses v^g^t. fossiles,' 

 p. 39 (These de G^ologie), Lille, 1876. 



