XIV] ISOETITES 67 



Isoetites. 



The generic name Isoetites was first used by Munster^ in the 

 description of a specimen, from the Jurassic lithographic slates 

 of Solenhofen in Bavaria, which he named Isoetites crociformis. 

 The specific name was chosen to express a resemblance of the 

 tuberous appearance of the lower part of the imperfectly pre- 

 served and indeterminable fossil to a Crocus corm. 



Impressions of Isoetes-like leaves from the Inferior Oolite 

 of Yorkshire figured by Phil lips ^ and afterwards by Lindley^ as 

 Solenites Murrayana were compared by the latter author with 

 Isoetes and Pilularia, but these leaves are now generally 

 assigned to Heer's gymnospermous genus Czekanowskia. An 

 examination of the structure of the epidermal cells of these 

 Jurassic impressions convinced me that they resemble recent 

 coniferous needles more closely than the leaves of any Pterido- 

 phyte. The genus Czekanowskia^ is recognised by several 

 authors as a probable member of the Ginkgoales. 



Isoetites Choffati. Saporta. 



The late Marquis of Saporta founded this species on two 

 sets of impressions from the Urgonian (Lower Cretaceous) of 

 Portugal which, though not foiind in actual organic connexion, 

 may possibly be portions of the same plant. Small relatively 

 broad tuberous bodies reaching a breadth of 1 cm. are compared 

 with the short and broad stem of Isoetes, which they resemble 

 in bearing numerous appendages radiating from the surface like 

 the roots of the recent species ; on the exposed face of the stem 

 occur scattered circular scars representing the position of roots 

 which were detached before fossilisation. Other impressions 

 are identified as the basal portions of sporophylls bearing 

 sporangia : these suggest the expanded base of the fertile leaves 

 of Isoetes with vertically elongated sporangia, some of which 

 have a smooth surface while in others traces of internal structure 

 are exposed ; the interior consists of an irregular network with 

 depressions containing carbonised remains of spores. 



1 MiiHster (42) p. 107, PI. iv. fig. 4. 2 Phillips (29) A PI. x. fig. 12. 



3 Lindley and Hutton A (34) PI. cxxi. ^ Nathorst (06); Seward (00) p. 278. 



