. The Bashford Dean memorial volume : archaic fishes. Fishes; Sharks; Fishes, Fossil. The Structure of Dinichthys 159 bone from the outside (B) and inside (A). In Dinichthys the complete ring is seldom found. It is known from a specimen of Dmichthys magnijicus Huss. & Br. in the Buffalo Museum. (Hussakof and Bryant, 1918; p. 41, fig. 11). Another specimen is preserved in the American Museum of Natural History. A third is figured by Newberry (1889). Text-figures 42 and 43 show the total reconstruction of the head of Dinichthys inter- medius Nwb. from the side and from above. From them we se
. The Bashford Dean memorial volume : archaic fishes. Fishes; Sharks; Fishes, Fossil. The Structure of Dinichthys 159 bone from the outside (B) and inside (A). In Dinichthys the complete ring is seldom found. It is known from a specimen of Dmichthys magnijicus Huss. & Br. in the Buffalo Museum. (Hussakof and Bryant, 1918; p. 41, fig. 11). Another specimen is preserved in the American Museum of Natural History. A third is figured by Newberry (1889). Text-figures 42 and 43 show the total reconstruction of the head of Dinichthys inter- medius Nwb. from the side and from above. From them we see that the proposed recon- structions are distinct from all that have been made heretofore. The head is much more compact and rounded in all directions; no sharp angles or processes protrude and there are no large spaces between the single plates. The head is sharply curved and thus the side and front margins of the head roof, SO and PSO, become nearly vertical. The lower jaw has at last obtained a distinct position. The nasal openings are also fixed. ° ' ' ^ f-^ I may mention here that the well-known "eye balls," , Text-figure 41. 1 -111 XT 1 /-,r,r,r^\ â 1 ⢠1 r. A piecc of the sclerotic ring in described by Newberry (1889) must, in accord with Stet- ^^^ hth â A { ' d â B f son's investigation (1930), be regarded as nasal capsules. outside. Probably they were placed behind the nasal openings, under the plate PrO. There is nothing to say about the sensory canals. I can only note that the short canal on P?v( unites the canal on PrO with that on SO, so that each eye opening is nearly encircled by a sensory canal. Finally, it can be pointed out, that the division of the head of Dinichthys into two regions, the head roof and the side plates, is quite like the division of the head in all the fishes into the brain case and the visceral region. The head roof in Dmichthys, like the brain case in the fishes, serves to protect the brain, eyes, ears and olfactory organ
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