144 FILICES. 



whole sorus. The sporangia are elongate-ovoid in shape with a long free 

 upper extremity, and dehisce by a slit on the inner side ; in S. Cyathea 

 they bulge out strongly on the dorsal side and acquire a somewhat different 

 shape. The wall of the sporangium is stout and of the same character all 

 round, and there is no indication of an annulus. If we compare this structure 

 of the parts of the fructification with that of our recent forms, the cohesion 

 of the sporangia into a roundish synangium directs us to Kaulfussia, while 

 section Eupodium of Marattia supplies an exact resemblance to the elongated 

 stalk-like base of the receptacle ; the free extremities only of the sporangia 

 with their long acuminations are quite peculiar to the genus. The nearest 

 ally of Scolecopteris, and of the group of Scolecopteris Cyathea in particular, 

 is Asterotheca, Presl (Fig. 13, E), which is founded on Pecopteris truncata 1 , 

 from the Coal-measures, and is still represented in later formations, as 

 is shown by P. Meriani which belongs to the genus and is of frequent 

 occurrence in the Keuper of Lunzer. The sori, which are perfectly spher- 

 oidal and are usually composed of six sporangia in close contact with one 

 another, are sessile and placed in a single row on each side of the median 

 nerve of each pinna. The sporangia have no annulus and resemble those of 

 Scolecopteris Cyathea in the bulging of the dorsal side, but they are flattened 

 at the top and end in a small and very short point. Owing to the firm 

 cohesion of the sporangia in the sorus, the dehiscence-slit cannot be certainly 

 perceived in the leaf-impressions, which are the only form of specimen that 

 we possess, but it is probably to be found in the steep inner margin. Closely 

 related to Asterotheca, as Stur has convincingly shown, is Ptychocarpus 

 hexastichus -, which is Diplazites, Gopp. in Stur ; but this name, since it is 

 based on the nervation of the fern-leaf, should not be employed. The 

 sori are placed in several rows on both sides of the median nerve in each 

 pinna, and are formed of a number of cohering sporangia disposed in a circle, 

 but they are in most cases laterally squeezed and crushed, so that in the 

 side-view we generally get sight of two adjacent sporangia separated from 

 one another by an intervening line. Asterocarpus Sternbergii 3, A. Meriani 4 , 

 and Cyathocarpus eucarpus 5 may be mentioned here as older figures of 

 fructifications of Asterotheca. 



The genus Renaultia, Stur (Pecopteris intermedia) 6 , in which the 

 shape of the lamina of the leaf is not known as our only specimens are in 

 sections of the pebbles of Grand' Croix, deviates more widely in some 

 respects from Scolecopteris and Asterotheca. Renault's drawing of the sorus 

 shows five sporangia disposed in a circle and opening on the inner side, 

 free above and adnate below to the fleshy receptacle, and distinguished by 

 their irregular ovoid form and occasional apical appendages, but above all 



1 Germar (1), t. 17. " Weiss (IX t. 11. ' Goppert (2), t. 6, ff. 1-3. 4 Heer (3), Trias, 

 t. 24. ' Weiss (1), tt. 9, 10. 6 Renault (2), vol. iii, t. 22. 



