94 Dr. W. C. Williamson on 



of some of the true SpJienopJiyllcEisee Nature, No. 1,201, p. ii). 

 It is obvious that we must now recognise an independent 

 family of Sphenophyllce,'wh.\ch., having points of affinity with 

 more than one existing family, exhibits other distinctive 

 features, which seem to separate it from all the recognised 

 groups. An extension of my plan is still more necessary in 

 dealing with the Lycopodiaccce. In my Memoirs I have 

 given provisional (not specific) names to several types of 

 Lepidodendroid plants ; but I have not always succeeded in 

 defining so clearly as is desirable the respective characteristics 

 of these types. What thus seems to be lacking will be 

 supplied in this second part of the Index. 



The recent discoveries in connection with SpJiejiopJiyllum 

 make it necessary to regard the lower half of p. 12, the whole 

 of p. 13, and the two upper lines of p. 14, as transferred to 

 the present one, under the head of SpJienophyllcB. They 

 need not be re-printed, but require to have added to them the 

 memoranda relating to Bozvinanites Daiusoni. M. Zeiller's 

 observations {see Nature, No. 1 201, p. 11), show that the fructi- 

 fication described by me under the above name is apparently 

 that of a true SpJienopJiylluni ; but connecting my discovery 

 of the peculiar form of its primary tracheal strand, with the 

 absolutely identical form of the same organ in the vegetative 

 stem of a SphenopJiyllum represented in Memoirs XVII., 

 PI. 15, fig. 19, we see that we have here a very distinct 

 modification of the SpJienophylloid type. The robustness of 

 its primary tracheal strand differs conspicuously from the 

 homologous slender triangles alike of the types figured by 

 M. Renault and myself ; hence, we have obviously equally 

 in the stem and the fruit-axis of my Bozvvianites Dawsoni, 

 what must be regarded as a distinct form of SpJLenophyllum. 

 This form most probably belongs to some one of the 

 structureless specimens which have already received specific 

 names ; but since we cannot at present identify it with any 

 one of them, I shall, for the present, recognise my stem and 

 fruit by the name of Sphenophylluvi Daivsoni. Will. 



