. Devonian fishes of Iowa. Fishes, Fossil; Paleontology; Paleontology. 88 IOWA GEOLOGICAL SURVEY. Fig. 12. Fig. 13. Fig. 12. Bothriolepis canadensis Whiteaves. Upper Devonian; Scaumenac Bay, Province of Quebec. Restoration of dorsal aspect, x § (alter Traquair). £z- m. occ, median occipital; I. occ, lateral occipital; ag., angular; pt. m., post-median; p. m., pre-median; I., lateral; e. I., extra-lateral; m., median; o., ocular; a. d. I., anterior dorso-lateral; a. m. d.,anterior median dorsal; p. d. I., posterior dorso-lateral; p. m. d., posterior median dorsal; d. a., dorsal anconeal; d. ar.
. Devonian fishes of Iowa. Fishes, Fossil; Paleontology; Paleontology. 88 IOWA GEOLOGICAL SURVEY. Fig. 12. Fig. 13. Fig. 12. Bothriolepis canadensis Whiteaves. Upper Devonian; Scaumenac Bay, Province of Quebec. Restoration of dorsal aspect, x § (alter Traquair). £z- m. occ, median occipital; I. occ, lateral occipital; ag., angular; pt. m., post-median; p. m., pre-median; I., lateral; e. I., extra-lateral; m., median; o., ocular; a. d. I., anterior dorso-lateral; a. m. d.,anterior median dorsal; p. d. I., posterior dorso-lateral; p. m. d., posterior median dorsal; d. a., dorsal anconeal; d. ar., dor- sal articular; e. m., external marginal; i. m., internal marginal; c, centrals of lower arm; m., marginals of lower arm; t., terminal. Fig. 13. The same from the ventral aspect, xs (after Traquair). mx., maxillary plate; s. /., semilunar; a. v. I., anterior ventro-lateral; p. v. I., posterior ventro-lateral; m. v., median ventral; car., ventral artic- ular; -v. a., ventral anconeal; c, centrals; m., marginals of lower arm; £., terminal. distal, though the proportion seems to vary; roughly speaking, however, the difference between the two portions is less than one-third of the longer. The proximal portion is, like that of Asterolepis, trigonal in transverse section, and the plates of which it is composed are also similar in number and arrange- ment, save that the dorsal anconeal (d. a.) is a smaller rounded element placed just at the "elbow" joint, whereby the external and internal marginals are allowed to come together for a con- siderable distance between it and the distal extremity of the dorsal articular (d. ar.). The two articulars, as noted in the generic diagnosis, meet together on the outer aspect over the external marginal; this relation, however, is not always clearly visible in the Canadian specimens, though demonstrable in many fragments from Scotland and Eussia. The lower or "fore" arm is slender and pointed, serrated along the external
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