CH. XLVl] THUYTES ; CUPRSSSINOCLADUS 303 



In the absence of well-preserved cones or anatomical data it is 

 possible that a comparative examination of cuticular membranes 

 might furnish useful results. It is, however, only rarely that such 

 information can be obtained and the only safe course to follow is to 

 use, with greater freedom than has generally been the practice, 

 provisional generic names which do not imply affinities to recent 

 genera. Provisional names that have reference only to vegetative 

 features should be superseded by designations denoting characters 

 of greater taxonomic significance when the necessary information 

 is available. As a preliminary to the description of a few selected 

 types it may be useful to consider the sense in which some generic 

 names have been employed and at the same time to state 

 whether the retention of certain names or their use in a modified 

 sense is advisable. 



Thuytes Brongniart. 



Brongniart^ instituted this term for 'Branches like those of 

 Thuya; fruit unknown.' The name, in the form Thuyites, had 

 been used a few years previously by Sternberg and it was adopted 

 by Unger^ as Ihuites for both sterile branches and cones similar to 

 those of the recent genus. Thuytes has been widely used for 

 vegetative branches agreeing generally in habit with those of 

 Thuya or Cupressus and some other Cupressineae, but with the 

 exception of some Tertiary species the designation has reference 

 in- nearly all cases to the form and arrangement of the leaves. 

 The employment of Thuytes in this wide sense is open to criticism 

 on the ground that in accordance with the usual practice specimens 

 so named would be considered to be more nearly related to Thuya 

 than to any other genus. It is therefore proposed to adopt the 

 generic designation Thuites only for such specimens as afford 

 evidence of close afiinity to the recent genus and to discontinue 

 its use for sterile shoots which suggest comparison not only with 

 Thuya but also with Cupressus, Libocedrus and other genera. 



CUPRESSINOCLADUS. Gen. nov. 



Goeppert's term Cupressites^ is retained for fossils which there 

 is reason for associating with Cupressus and should not be employed 



1 Brongniart (28) A. p. 109; Seward (04) B. p. 140.~ 



2 Unger (50) A. p. 346. ' Goeppert (50) p. 183. 



