568 Reviews — Dr. D. H. Scott — Studies in Fossil Botany/. 



Dawsoni is taken as the type of SpTienopliyllum fructification, and is 

 fully described. It might be remarked here, that S. Dawsoni is 

 almost certainly the fruit of S. cuneifolium, Sternb., sp., of which 

 probably S. plurifoliatum is the stem. The fructifications of other 

 species of Sphenophyllum are described or referred to, and though 

 the vegetative organs of all tbe species of Sphenophyllum have 

 a great similarity, the arrangement of the sporangia in some of 

 the species varies considerably : so much is this the case, that the 

 genus as presently employed must be regarded more in the light of. 

 a group than a genus ; but in vegetable paleeontology the imperfect 

 knowledge of many critical characters makes it most unwise to treat 

 fossil genera in the restricted manner in which one would proceed 

 in dealing with existing plants. Although Cheirostrohus is here 

 placed in the Sphenophyllales, its connection with Sphenophyllum does 

 not appear to be very close. 



The Lycopodiales occupy Lectures v-vii, and contain descriptions 

 of Lepidodendron, Lepidophloios, Sigillaria, and Stigmaria. We 

 cannot agree with Dr. Scott's treatment of Halonia and Ulodendron. 

 Halonia is correctly referred to Lepidophloios as its fruiting branch 

 (p. 156), and Ulodendron in part to Lepidodendron and Sigillaria 

 (p. 152) ; but, again, it is said : " What, then, was the nature of 

 the Halonial branches, which were evidently not characteristic of 

 a separate genus, but occurred as terminal ramifications on ordinary 

 Lepidodendroid stems?" (p. 158). Again, "Williamson, however, 

 described a specimen with multiseriate, quincuncially arranged scars 

 of the Ulodendron character, and also a Halonia with the tubercles 

 in two series, so this distinction loses its value" (pp. 158-159). 

 As references for this statement Dr. Scott mentions Williamson's 

 figures given in Mem, xix, pi. vi, figs. 22 and 25a. Now the 

 " cortex of Lepidophloios, with rows of Ulodendroid fructiferous 

 scars, arranged as in Halonia regularis " (Williamson, I.e., p. 33), 

 shows a typical specimen of a fruiting branch of Lepidophloios 

 with leaf and cone scars, and does not possess a single Ulodendroid 

 character ; whereas Williamson's fig. 22, " a young fructiferous 

 Halonial branch, with its tubercles in two lateral series" (I.e., p. 33), 

 is decorticated, and does not exhibit any characters by which it can 

 be referred with certainty to either Lepidophloios, Lepidodendron, or 

 Sigillaria ; and as all the specimens with two roios of large scars 

 which have shoion the leaf-scars, have invariably belonged to Lepido- 

 dendron, Sigillaria, or Bothrodendron, there seems little warrant for 

 referring this specimen to Lepidophloios, especially when no specimen 

 has ever been described or figured wherein a distichous arrangement of 

 the fructiferous scars has been found associated with the Lepidophloios 

 leaf-scar. We also know the specimen referred to on p. 160, and 

 here, also, there is absolutely no evidence for including it in Lepido- 

 phloios rather than referring it to Sigillaria discophora, where the 

 fructiferous scars were in two rows, and the other characters of this 

 specimen would seem to refer it to this species. We would naturally 

 expect to find that the internal organization of two such closely 

 allied genera as Lepidodendron and Lepidophloios possessed an 



