88 LYCOPODIALES [CH. 



dimensions those of recent forms and on the other hand were 

 smaller than those of the Palaeozoic arborescent species. 



There can be little doubt that some of the Mesozoic and 

 Tertiary species included under Lycopodites agree more closely 

 with the recent genus Selaginella than with Lycopodium, but 

 this does not constitute an argiiment of any importance against 

 the restricted use of the designation Selaginellites which we 

 have adopted. From a botanical point of view the various 

 records of Lycopodites and Selaginellites have but a minor im- 

 portance; they are not sufficiently numerous to throw any light 

 on questions of distribution in former periods, nor is the preser- 

 vation of the material such as to enable us to compare the fossil 

 with recent types either as regards their anatomy or, except in 

 a few cases, their sporangia and spores. The Palaeozoic species 

 are interesting as revealing less reduction in the number of spores 

 produced in the megasporangia. Among existing Pteridophytes 

 the genus Isoetes agrees more closely than Selaginella, as regards 

 the number of megaspores in each sporangium, with such fossils 

 as Selaginellites Suissei and S. elongatus. 



It would seem that in most Palaeozoic species heterospory 

 had not reached the same stage of development as in the recent 

 genus Selaginella in which the megaspores do not exceed four 

 in each sporangium. In Selaginellites primaevus, however, the 

 heterospory appears to be precisely of the same type as in 

 existing species. 



Lycostrobus. 



The generic name Lycostrobus has recently been instituted 

 by Nathorst' for certain specimens of a lycopodiaceous strobilus, 

 from the Rhaetic strata of Scania, which he formerly referred to 

 the genus Androstrohus'\ 



Lycostrobus Scotti Nathorst. Fig. 139. 



The fossil described under this name is of special interest as 

 affording an example of a Mesozoic lycopodiaceous cone com- 

 parable in habit and in size with some of the largest examples 

 1 Nathorst (08). = Nathorst (022j p. 5, PI. i. fig. 1. 



