XXXV] 



PACHYTBSTA 



326 



interlocking of nucellus and canopy in Lagenostoma, as also with 

 the ruminated endosperm of Torreya. 



We have no definite information as to the plants which bore 

 Pachytesta, but it is probable that they were members of the 

 MeduUoseae. Grand'Euryi beheves Pachytesta to be the seed 

 of Alethopteris Grandini, though this view requires confirmation. 

 This author figures several Pachytesta seeds attached in two obhque 

 rows to a comparatively slender axis which may be the rachis of 



Fig. 497. Pachytesta. Transverse section of a seed showing the exotesta, ex, with 

 sclerous layers and vascular strands (black), the endotesta (dotted), the 

 nucellus with its ring of vascular bundles, n, and the prothaUus, p. The 

 three radial plates in the exotesta are seen at a, b, c, with the trabeculae, t, 

 and internal to these are the grooves in the endotesta engaging with ribs on the 

 nucellus, nr. (After OUver.) 



a large compound frond^. Eenault and Zeiller^ have figured 

 specimens of P gigantea and P. incrassata from Commentry 

 which afford a good idea of the form of these large seeds; the 

 genus is recorded also from Gard, Blanzy*, and other locahties. 

 Kidston^ described a large oval seed, blunt at each end, from the 

 Middle Coal Measures of Lancashire as Carpolithus Wildii which 

 he thinks may be alHed to Pachytesta, but adds, 'I do not think 

 we are justified in placing mere impressions of plants in genera, 



1 Grand'Eury (04). 



2 Grand'Eury (90) A. PL vm. fig. 3; (77) A. PI. xvi. fig. 5. 

 » Eenault and ZeiUer (88) A. PI. 73. 



* Zeiller (06) B. p. 229. " Kidston (92) p. 8. 



