A guide to the fossil invertebrate animals in the Department of geology and palaeontology in the British museum (Natural history) . and occur in Bhynchonella,Spirifer (Fig. 59), Terehrahda, and allied forms: such generaconstitute the Order Telotremata. The arms are oftensupported by a calcareous skeleton, the shape of which is ofgreat importance in classifying fossil brachiopods. Thus,the Telotremata branched into loop-bearing forms (Diagram 9and Fig. 60, Magellania) and spire-bearing forms (Diagram 9,Atrypa, and Fig. 59, Spirifer). The Orders Atremata and Neotremata are equivalent tosuccessiv
A guide to the fossil invertebrate animals in the Department of geology and palaeontology in the British museum (Natural history) . and occur in Bhynchonella,Spirifer (Fig. 59), Terehrahda, and allied forms: such generaconstitute the Order Telotremata. The arms are oftensupported by a calcareous skeleton, the shape of which is ofgreat importance in classifying fossil brachiopods. Thus,the Telotremata branched into loop-bearing forms (Diagram 9and Fig. 60, Magellania) and spire-bearing forms (Diagram 9,Atrypa, and Fig. 59, Spirifer). The Orders Atremata and Neotremata are equivalent tosuccessive stages of the Inarticulata, and are most abundantin the earlier Palseozoic rocks. From them the Protremataand Telotremata arise as divergent groups, which togetherare the equivalent of the Articulata. The Protremata weredominant in later Palseozoic time; the Telotremata inMesozoic. I 114 GUIDE TO THE FOSSIL INVEETEBRATE ANIMALS. Gallery In addition to the particular specimens already pointedsrZlcases attention may be directed to the following. Specimens10 & 11. brought from the Arctic Eegions by various British expedi-. FiG. 59.—An example of the spire-bearing Telotremata, Spirifer Limestone. The shell is seen from the side of thebrachial valve, and portions of that valve are broken away, exposingthe spires that support the arms of the lophophore. Between theumbones of the peduncular and brachial valves is seen the delthyrium,partly filled in by the deltidial plates that have met and fused abovethe foramen into a single deltidium. (From the Cambridge NaturalHistory.)
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