Fig. 31 in Braincase Of The Upper Devonian Shark Cladodoides Wildungensis (Chondrichthyes, Elasmobranchii With Observations On The Braincase In Early Chondrichthyans

Fig. 31. Fragmentary acid­prepared occipital region of an undetermined (ctenacanth?) shark braincase, USNM 299647, St. Louis Limestone, Alton, Illinois. (A) Dorsal view, anterior to top; (B) anterior view. Note the extensive notochordal sheath supported by a median subnotochordal septum and large paired ''chambers'' forming prominent convexities ventrally between the median groove and paired aortic canals. Scale bar = 5 cm.