The Annals and magazine of natural history; zoology, botany, and geology . lder rocks, and might be thought superfluous. But thequestion is somewhat complicated, and cannot well be decidedunless in view of all the circumstances. Besides this, it is oneupon which any good naturalist is perfectly competent to givean opinion although specially engaged in other of these have access to works on palaeozoic fossils; andtherefore, for the convenience of such as may feel inclined toinvestigate the subject, it is desirable to bring all the facts to-gether. There is no dispute about the e
The Annals and magazine of natural history; zoology, botany, and geology . lder rocks, and might be thought superfluous. But thequestion is somewhat complicated, and cannot well be decidedunless in view of all the circumstances. Besides this, it is oneupon which any good naturalist is perfectly competent to givean opinion although specially engaged in other of these have access to works on palaeozoic fossils; andtherefore, for the convenience of such as may feel inclined toinvestigate the subject, it is desirable to bring all the facts to-gether. There is no dispute about the extent of the geneia; and there-fore the details of the internal characters need not be given. Itis purely a question of natural-history ethics, if I may be per-mitted to use such a term. 1. History and Extent of the original Genus. The original description was published in the Synopsis ofthe Carboniferous Fossils of Ireland,^ in 1844. From this workI shall make some extracts, and shall introduce along with theoriginal figure two others to further illustrate the Fig. 1. Copy of the original figure given by MCoy (without a specificname) to ilhistrate his idea of the general form of an Athyris. Fig. 2. Spirigera concentrica, Von Buch. The form is copied fromDavidsons Monograph of the British Devonian Brachiopoda,pi. 3. fig. 13, Pal. Soc. Mon. for 1862. The right-hand side is,in this copy, a httle restored, and the aperture in the beak madelarger than it is in the original figure. Fig. 3. Athyris tumida, Dalman. Copied from Davidsons General In-troduction, pi. 6. fig. 73. The following extracts are from ^ICoys work above referredto:— The family Delthyridse appears to be divided into the five fol-lowing genera :—1. Spirifera, Sow., composed of those longitudinallyribbed species in which the hinge-line is equal to, or exceeds, thewidth of the shell, the cardinal area with parallel sides, the cardinalteeth of the ventral valve [now called the dorsal valve] large, spirall
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