THE TRIASSIC PERIOD. 



213 



Palaeozoic group of the Rugose corals has no known repre- 

 sentative here, its place being taken by corals of Secondary 

 type (such as Montlivaliia, Synastrcea, &c.) 



The Echinodenns are represented principally by Crinoids, 

 the remains of which are extremely abundant in some of the 

 limestones. The best-known species is the famous " Lily- 

 Encrinite" (Encrmus liluformis, fig. 142), which is character- 

 istic of the Muschelkalk. In this beautiful species, the flower- 

 like head is supported upon a rounded stem, the joints of 

 which are elaborately articulated with one 

 another ; and the fringed arms are com- 

 posed each of a double series of alter- 

 nating calcareous pieces. The Palaeozoic 

 Urchins, with their supernumerary rows of 

 plates, the Cystideans, and the Pentremites 

 have finally disappeared; but both Star- 

 fishes and Brittle-stars continue to be rep- 



Fig. 142. Head and 

 upper part of the column 

 of Encrinus liliiformla. 

 The lower figure shows 

 the articulating surface 

 of one of the joints of the 

 column. Muschelkalk, 

 Germany. 



period. Remains of 



Fig. 143. Aapidura loricata, a Triassic Ophluroid. 

 Muschelkalk, Germany. 



resented. One of the latter namely, the 

 Aspidura loricata of Goldfuss (fig. 143) is 

 highly characteristic of the Muschelkalk. 



The remains of Articulate Animals are 

 not very abundant in the Trias, if we except 

 the bivalved cases of the little Water-fleas 

 (Ostracoda), which are occasionally very 

 plentiful. There are also many species 

 of the horny, concentrically-striated valves 

 of the Estheria (see fig. 122, b}, which 

 might easily be taken for small Bivalve 

 Molluscs. The "Long-tailed" Decapods, 

 of the type of the Lobster, are not with- 

 out examples, but they become much more 

 numerous in the succeeding Juriassic 

 insects have also been discovered. 



