Fig. 141.—Triassic Conifers and Cycads. a, Voltzia (Schizoneura) heterophylla, portion of a branch, Europe and America; b, Part of the frond of Pterophyllum Jœgeri, Europe; c, Part of the frond of Podozamites lanceolatus, America. of California and Nevada have likewise yielded numerous remains of marine Invertebrates. The Protozoans are represented by Foraminifera and Sponges, and the Cœlenterates by a small number of Corals; but these require no special notice. It may be mentioned, however, that the great Palæozoic group of the Rugose corals has no known representative here, its place being taken by corals of Secondary type (such as Montlivaltia, Synastœa, &c.)
The Echinoderms 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" (Encrinus liliiformis, fig. 142), which is characteristic of the Muschelkalk. In this beautiful species, the flower-like head is supported upon a rounded stem, the joints
Fig. 142.—Head and upper part of the column of Encrinus liliiformis. The lower figure shows the articulating surface of one of the joints of the column. Muschelkalk, Germany. of which are elaborately articulated with one another; and the fringed arms are composed each of a double series of alternating calcareous pieces. The Palæozoic 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 represented. One of the latter—namely, the
Fig. 143.—Aspidura loricata, a Triassic Ophiuroid. Muschelkalk, Germany. 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 Estheriœ (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 without examples but they become much more numerous in the succeeding Jurassic period. Remains of insects have also been discovered.
Amongst the Mollusca we have to note the disappearance, amongst the lower groups, of many characteristic Palæozoic types. Amongst the Polyzoans, the characteristic "Lace-corals," Fenestella, Retepora,[22] Synocladia, Polypora, &c., have become apparently extinct. The same is true of many of the ancient types of Brachiopods, and conspicuously so of the great family of the Productidœ, which played such an important part in the seas of the Carboniferous and Permian periods.
[Footnote 22: The genus Retefora is really a recent one, represented by living forms; and the so-called Reteporœ of the Palæozoic rocks should properly receive another name (Phyllopora), as being of a different nature. The name Retepora has been here retained for these old forms simply in accordance with general usage.]
Bivalves (Lamellibranchiata) and Univalves (Gasteropoda) are well represented in the marine beds of the Trias, and some of the former are particularly characteristic either of the formation as a whole or of minor subdivisions of it. A few of these characteristic species are figured in the accompanying illustration (fig. 144). Bivalve shells of the genera Daonella (fig. 144, a) and Halobia (Monotis) are very