MICRODICTYON 137 
Dunkeri (Schenk), but the venation, as shown in an enlarged 
pinnule, readily distinguishes this genus from the JLcrodictyon 
type. The specimen represented in fig. 1, pl. vil. of Andrae 
shows the basal ends of six pinne attached to the summit of a 
short rachis, suggesting a close connection, as regards habit, with 
Matonidium. Schenk’s figures of Zaccopteris Minsteri 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 If Dunkeri; it is certainly very similar, and 
without doubt should be removed to Saporta’s genus. The second 
species, C. aspleniordes, shows a different venation. 
This genus is thus defined by Debey and Ettingshausen * :— 
‘‘Frons pinnata (vy. bi- v. pluries-pinnata). Venze ramosissime, 
ad costas medianas in areolas polygonas confluentes, marginem 
versus simplices v. furcatee. 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. Rachis 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 DMicrodictyon. In coarse quartzose sandstone. Cf. Schenk, 
Palzontographica, vol. xxiii. pl. xxvii. fig. 10, and pl. 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 Coll. 
V. 2199 and V. 2298. Fragments. Ecclesbourne. Rufford Coll. 
529420. Fragment. Ecclesbourne. 
Presented by J. F. H. Peyton, Esq. 
1 Denkschr. k. Ak. Wiss. math.-nat. Cl. 1859, vol. xvii. p. 206, pl. iil. 
