Oeological Society. 293 



venti'iijl. He considered the presence of tentacular arms to be 

 doublful. These observations were in accord with those of 

 Huxley, who, in his 'Memoir' already cited, stated that he had 

 ' not been able to make out more than six or seven arms in 

 any specimen, nor has any exhibited traces of elongated tentacula, 

 though the shortness of the arms which have been preserved would 

 have led one to suspect their existence.' 



The speaker regarded certain markings sometimes to be seen on 

 the guard as indicating that during the life of the animal the 

 guard was almost, if not entirely, covered by the mantle, in which 

 case it was higldy in\probable that the guard was pushed into the 

 soft mud of the sea-bottom in order to act as an anchor. 



He considered tlie animal to have been a free swimmer, swimming 

 forward ordinarily, but when desirable, capal)le also of sudden and 

 rapid propulsion backwards. 



A short discussion followed, and tlie thanks of the Fellows 

 present were accorded to Mr. Crick for liis lecture. 



December 2()th, 11)10.— Dr. Alfred Hurker, F.R.S., President," 

 in the Chair. 



Marie C. Stopes, D.Sc, Ph.D., gave an account of some 

 recent researches on Mesozoic 'Cycads' (Bennetti- 

 tales), dealing particularly with recently-discovered ])etrified 

 remains which reveal their cellular tissues in microscopic prepara- 

 tions. To make the significance of the various fossil forms clear, 

 Dr. Stopes first showed some lantern-slides of living Cycads, and 

 then pointed out that it was in their external features and in their 

 vegetative anatomy only that the fossil ' Cycads ' were like the 

 living forms ; the most important features, the rejjroductive organs, 

 differ profoundly in the two grou])s. and the fossils were funda- 

 mentally distinct, not only from the living (h^cads, but from all 

 other living or fossil families. 



The fossils representing the group that are most frequently 

 foimd are (a) trunks, generally more or less imperfect casts or 

 partial petrifactions, and sometimes excellent petrifactions pre- 

 serving anatomical details and cell-tissues; {h) iiupressions of the 

 foliage. Not infrequent are the detached imjjressions of incomplete 

 'flowers' or cones, of one cohort (the Williamsoneis), while 

 petrified fructifications are numerous in some of the well-petrified 

 trunks of the Bennettitese. The described species of the group 

 I'un into hundreds, but probably many of tliese duplicate real 

 species, because the foliage, trunks, pith-casts, various portions of 

 tlie fructifications, etc., have often been separately found and 

 named. In very few cases have the different parts been correlated. 

 The species of the foliage are the most generally known, as they 

 are the most readily recognized with the naked eye ; they have 

 been described under a variety of generic names. 



