A New Part of Pachytheca. 73 



EXPLANATION OF PLATES. 

 PLATE XVII. 



Fig. i. Side view of cup of Pachytheca ( x 14). 

 Fig. 2. The same from above ( x 14). 

 Fig. 3. The same in vertical section ( x 25). 

 Fig. 4. Hairs from the lower part of outside of cup ( x 61). 

 Fig. 5. a. The cup natural size, 5. b. The cup natural size, showing how the 



rested in it. 



PLATE XVIII. 



Fig. i. Patfii't/ieca-sphere (from cup) showing portion of shiny outer layer 



(x 14). 



Fig. 2. Section through portion of same ( x 55). 

 Fig. 3. Section through another (marginal) portion, including shiny outer 



layer ( x 86). 



Fig. 4. Tangential section through another PatAytfoca-sphere ( x 125). 

 Fig 5. Portion of same ( x 375). 

 Fig. 6. Diagrammatic section through sphere and cup. 



NOTE. Figs. 4 and 5 (plate xvm.) are from a section sent me by Mr. Storrie. 

 They were cut from a Pachytheca obtained from the same bed as the one described. 

 The section is tangential near the periphery, but a portion of the central core is 

 shown. Fig. 5 shows both central and peripheral tissues, and the arrangement of 

 the peripheral tubes shows inconsistencies with any known plant structure, a con- 

 dition which may or may not be due to their state of preservation. For example, 

 the tubes cut transversely sometimes appear between those cut obliquely, and 

 sometimes within them, even under the most careful focussing. 



