. Bulletin of the British Museum (Natural History), Geology. THE HEAD OF DIPTERUS VALENCIENNESI g shape and extent of the dermal bones of the cranial roof in Osteolepiformes . . are not always to be explained by various fusions, etc. ", which comes quite near to WestoU's (1944 : 114) assertion that " the compound form (of nomenclature) . . expresses no more than geographical extent . .", and certainly weakens the argu- ment for too rigid adherence to the hypothesis of universal fusion without unduly encouraging those who pin their faith overmuch on the apparently contradictory i
. Bulletin of the British Museum (Natural History), Geology. THE HEAD OF DIPTERUS VALENCIENNESI g shape and extent of the dermal bones of the cranial roof in Osteolepiformes . . are not always to be explained by various fusions, etc. ", which comes quite near to WestoU's (1944 : 114) assertion that " the compound form (of nomenclature) . . expresses no more than geographical extent . .", and certainly weakens the argu- ment for too rigid adherence to the hypothesis of universal fusion without unduly encouraging those who pin their faith overmuch on the apparently contradictory idea of "loss and invasion "—" aut Caesar aut nihil " may be a good political precept but it is usually a poor biological principle—indeed, Truth in Nature has a habit of falling between two schools of thought. In spite of what has been said by their proponents concerning the advantages of either philosophy for establishing the identity or homologies of bones or their supposed components in Dipnoi, it is in practice often very difficult to identify bones by any system satisfactorily, and important mistakes and man}^ doubtful identifications have been made on both sides. Not the smallest source of error has been due to attempts to establish the course of the canals by the openings of the tubuli on the surface of the bones; and this in the nature of things is often inevitable, since it is not always desirable or possible to dissect out the Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original British Museum (Natural History). London : BM(NH)
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