15 



IV. Phytolithus parmatus. This fossil is figured by 

 Scheuchzer, Herbar. Diluv. p. 1 1 9 : it is distinguishable 

 by a singular organization observable on its surface ; a 

 series of circular or oval scutellae, or shields, are placed 

 close to each other in a right line across the surface. 

 There are three distinct appearances ; two of these, the 

 epidermal and ligneous, somewhat resemble each other, but 

 the latter is seldom met with. "In the epidermal," Mr. 

 Steinhauer observes, " the parmae are surrounded by a 

 raised margin, the included disk swells towards the central 

 umbo or boss in curiously disposed rugae, and the boss is 

 generally more or less excavated in the centre. These 

 configurations 01:1 the surface of the shields vary in almost 

 every specimen ; yet so that it is not difficult to trace their 

 analogy and the identity of their different marks. The 

 raised margin is constant, and there is always a tendency of 

 the other lines and protuberances towards the centre ; not 

 in the direction of the radii, but in a manner slightly re- 

 sembling the figures on the back of an engine-turned watch, , 

 produced by describing several circles whose centres are 

 situate in the circumference of another circle round the 

 middle of the plate. 



V. Phytolithus imbricatus, Organic Remains, Pl.l,Jig.Q. 

 This is the fossil figured by Mr. Martin, PL III, Jig. 4, 

 and to which Mr. Steinhauer has given the name of Phy- 

 tolithus Martini. The trunk is round and tapering, some- 

 times branched, leafy and covered with scales. Leaves 

 crowded, seemingly one from each scale ; subulate, marked 

 with a strong rib : scales rhomboidal, sharp pointed, slightly 

 carinated or keeled, close, imbricate, covering each other in 

 such a manner that the whole surface of the stem appears 

 regularly divided into rhombs. 



VI. Phytolithus transversus of Steinhauer appears to be 

 the fossil already referred to, page 13, and figured (PI. I, 

 Jig. S,aJ, in illustration of Phytolithus verrucosus. 



