MACKIE — FIRST TRACES OF THE SUCCESSION OF LIFE. 



423 



varied : cliiselled, ribbed, striated, and cancellated with every kind 

 and description of line, groove, and ridge, their markiags are only 

 exceeded in their diversity by the infinity of the vivid hues and 

 curious designs of their beautiful paintings. 



The pearly lustre and nacreous prismatic tints may have vanished 

 from the remains of those soft-bodied inhabitants of the fossil shells, 

 but the beauty of their forms and the delicacy of their markings are 

 truly preserved by Nature's unerring hand in the crystalline marble 

 into which their shells in the lapse of ages have been turned. Sunk 

 into pits, or attached to protuberances, smooth, or interlocking, even 

 that most primitive of all attachments, the ligamental hinge, is never 

 alike in two species, is never repeated, as though infinite change was 

 part of the great scheme of creation, an attribute of the Deity, to 

 be manifested alike in pleasure or pain, in the world or the universe, 

 and in the grandest, or most trivial and simple of things. 



The Lingulae of North Wales were first discovered by Mr. Davis, 

 in 1845, near Tremadoc, and in the same Lower Silurian beds are 



Lign. 7.— 0I.BIJ-U8 MiCBTTBTTS 



( nat. size) . From the figure 

 in the *' Decades of the 

 Creological Survey," No. ii.. 



plate ix. Prom a speclm^ 

 from Trawsfynydd, Meri- 

 onethshire. 



associated the remains of several species of trilobites, namely, Olenus 

 micrumsj Agnostus pisiformis, and a Paradoxides, supposed by 



Lign. 8.— Agitosttts pisipobmis. 

 From Angelin's " Palaeonto- 

 logia Suecica," pt. i., 1852, tab. 

 vi., fig. 7. [Syn.: BntomoUthus 



paradoxus var. pisiformls. 

 Linnaeus Iter. Scan., p. 122. 

 Syst. Nat,, ed. xvl., vol. iii., 

 p. 160.] 



