MICEODICTTON- 137 



Dunkeri (Schenk), but the venation, as shown in an enlarged 

 pinnule, readily distinguishes this genus from the Microdictyon 

 type. The specimen represented in fig. 1, pi. vii. of Andrae 

 shows the basal ends of six pinnes attached to the summit of a 

 short rachis, suggesting a close connection, as regards habit, with 

 Matonidium. Schenk's figures of Laccopteris Miinsteri clearly 

 demonstrate the form of frond characteristic of this class of ferns. 



The figures of Carolopteris aquensis, Deb. and Ett., show a 

 type of venation which appears to conform exactly to that of 

 Microdictyon, and the habit is equally similar. Possibly C. aquensis 

 is identical with M. Dunkeri \ it is certainly very similar, and 

 without doubt should be removed to Saporta's genus. The second 

 species, C. asplenioides, shows a different venation. 



This genus is thus defined by Debey and Ettingshausen J : 



"Frons pinnata (v. bi- v. pluries-pinnata). Yense ramosissimse, 

 ad costas medianas in areolas polygonas confluentes, marginem 

 versus simplices v. furcatae. Sori ad costam medianam biseriales, 

 magni, orbiculares, globoso-depressi, areolis majoribus, venis 

 reticulatis circumscriptis tectisque insidentes, indusiati, apice 

 orbiculatim dehiscent." 



This definition is very similar to Saporta's diagnosis of Micro- 

 dictyon. 



Specimen without Registered Number. Eachis 5*5 cm. long. 

 Ultimate segments show no details of venation ; they are alternate, 

 linear and of uniform breadth. On each side of the midrib occur 

 distinct round projections, the regularly-placed sori characteristic 

 of Microdictyon. In coarse quartzose sandstone. Cf. Schenk, 

 Palaaontographica, vol. xxiii. pi. xxvii. fig. 10, and pi. xxviii. 

 fig. 11. 



V. 719. No details shown. Sori indicated by depressions in the 

 rock surface. Heathfield. Purchased. 



V. 2214. Probably the same species, but venation hardly visible. 

 Ecclesbourne. Rufford Colt. 



V. 2199 and V. 2298. Fragments. Ecclesbourne. Rufford Coll. 

 52942a. Fragment. Ecclesbourne. 



Presented ly J. F. H. Peyton, Esq. 



1 Denkschr. k. Ak. Wiss. math.-nat. Cl. 1859, vol. xvii. p. 206, pi. iii. 



