. Bulletin of the Museum of Comparative Zoology at Harvard College. Zoology. 30 bulletin: museum of comparative zoology In Dinichthys (PI. 3) we find that the posterior wall of the broad an- terior division of the occipital region has approximately the same shape. It consists of two heavy plates of bone (fig. 2, A'.Y,) (the exoccipitals of Woodward, 1922, fig. 4D). Lying between them and somewhat lower, is a forward-projecting tongue of bone, springing from the posterior girder of the cranial shield. It lies dorsad to the posterior narrow divi- /. Fig. 2.— D. lerrelli. Interior of cranial shie
. Bulletin of the Museum of Comparative Zoology at Harvard College. Zoology. 30 bulletin: museum of comparative zoology In Dinichthys (PI. 3) we find that the posterior wall of the broad an- terior division of the occipital region has approximately the same shape. It consists of two heavy plates of bone (fig. 2, A'.Y,) (the exoccipitals of Woodward, 1922, fig. 4D). Lying between them and somewhat lower, is a forward-projecting tongue of bone, springing from the posterior girder of the cranial shield. It lies dorsad to the posterior narrow divi- /. Fig. 2.— D. lerrelli. Interior of cranial shield drawn from specimen in Plate 3. Heavy line out- lines boundaries of chondrocranium, X, X plates bounding; posterior wall of anterior division of occipital region, Y, Y possible cavities for branchial apparatus, Z posterior division of occipital region. sion of the occipital region. This tongue is hollowed at its anterior end. There is no median suture as shown by Newberry and Smith Wood- ward. The latter considers this marks the end of the brain case (1922, p. 33). Stensio, however, maintains that the brain case continues to the rear of the cranial shield and shows it thus in his restoration (1925, fig. 23B). In view of his discoveries in Macropetalichthys, this latter position seems to be correct. As can readily be seen in Plate 3, there is a deep, bilobed depression centrally situated at the posterior margin of the cranial shield. The two halves are separated by a low ridge pos- teriorly, and are bounded by heavy girders of bone which form a tri- angle. This was occupied, very probably, by the posterior end of the occipital region, and the well-marked cranio-spinal processes (Stensio,. 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 Harvard University. Museum of Comparative Zoology. Cambridge, Mass. :
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