. Conodonts of the Lower Border group and equivalent strata (lower carboniferous) in Northern Cumbria and the Scottish Borders, Conodonts; Paleontology; Paleontology; Conodonts; Paleontology. The three morphotypes of T. varians described herein differ only in blade position and serve as aids to discussion of intraspecific variation. These morphotypes are not randomly distributed. Most American T. varians faunas are dominated by morphotype I (, Branson and Mehl, 1941b; Thompson and Goebel, 1969; Nicoll and Rexroad, 1975); the limited Irish fauna of Austin and Mitchell (1975) is domina
. Conodonts of the Lower Border group and equivalent strata (lower carboniferous) in Northern Cumbria and the Scottish Borders, Conodonts; Paleontology; Paleontology; Conodonts; Paleontology. The three morphotypes of T. varians described herein differ only in blade position and serve as aids to discussion of intraspecific variation. These morphotypes are not randomly distributed. Most American T. varians faunas are dominated by morphotype I (, Branson and Mehl, 1941b; Thompson and Goebel, 1969; Nicoll and Rexroad, 1975); the limited Irish fauna of Austin and Mitchell (1975) is dominated by morphotype II; Northumberland trough faunas are dominated by morphotype III (Armstrong and Purnell, 1987; this study). This geograph- ical distribution might suggest that morphotypes I, II, and III represent three subspecies (sensu Mayr, 1969:41); however, the morphotypes are not geographically mutu- ally exclusive. The separate populations show consi- derable overlap in their ranges of variation, and the distribution of morphotypes probably reflects different bias within the same range of variation in separate geographical areas. The holotype of T. varians, for example, although part of an American morphotype I- dominated fauna, is intermediate between morphotypes I and II. Taphrognathus cravenus (Metcalfe) is distinguished from T. varians primarily by the lateral flare or "winged" appearance of the anterior end of the right parapet. From the available material, it is unclear whether or not this character is consistently developed and of sufficient importance to maintain T. cravenus as a separate species. One of the specimens figured by Metcalfe (1981, pi. 11, fig. 2) lacks this character and is included in synonymy with T. varians. Metcalfe (1981) also reported a single specimen of T. rhodesi Austin (in Austin and Mitchell, 1975). This specimen is overgrown, but appears to lack the diagnostic platform ornament of T. rhodesi and is probably T. varians. The app
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