. Bulletin of the Museum of Comparative Zoology at Harvard College. Zoology. 400 Bulletin Museum of Comparative Zoology, Vol. 142, No. 4. Figure 5. Cera/os/efhus bicornis. Dorsal view of anterior part of skull witfi jaws greatly protracted. Compare Fig. 6C. stethus are perhaps even more specialized, for they include a number of hitherto un- reported ossified elements, some of which are without knowai osseous homologues in atherinoids or cyprinodontoids or even analogues in other teleosts. These evidently neomorphic structures, apparently present only in phallostethoids, are functionally in- vo
. Bulletin of the Museum of Comparative Zoology at Harvard College. Zoology. 400 Bulletin Museum of Comparative Zoology, Vol. 142, No. 4. Figure 5. Cera/os/efhus bicornis. Dorsal view of anterior part of skull witfi jaws greatly protracted. Compare Fig. 6C. stethus are perhaps even more specialized, for they include a number of hitherto un- reported ossified elements, some of which are without knowai osseous homologues in atherinoids or cyprinodontoids or even analogues in other teleosts. These evidently neomorphic structures, apparently present only in phallostethoids, are functionally in- volved in the extreme protrusibility of the jaws (evidently including closure of the jaws in protruded position). The new bones, discussed below, are paired ele- ments, named as follows (in order of oc- currence anteroposteriorly): paradentary, maxillomandibular, pararostral, and sub- maxillary bones. Bones in upper jaw: paired premaxil- laries, maxillomandibularies, maxillaries, pararostrals, and submaxillaries; in lower jaw: dentaries, paradentaries, articulars, angulars, and coronomeckelians. Premaxil- laries and dentaries with a single row of conical teeth; other jaw bones and palate toothless. Proximal third of premaxillary with eight to ten relatively small teeth, middle third with about ten enlarged teeth, distal third toothless. Dentaries with three to five very small (vestigial ?) teeth near symphysis; otherwise toothless. Ascending premaxillary processes slender, elongate (their length almost equal to a third of cranial length). Posteriorly directed, broad-based, roundec 1 processes ("articular processes") arising at midlength of prcniaxillaries; sucl processes (either rounded or pointed) characteristic of many atherinoids, are usu ally (invariably ?) absent in cyprin odontoids. Several atherinoids have slender elongate ascending processes as in Cerate stcthiis; ascending processes in cyprin- odontoids usually (invariably ?) relativel) short, broad-based, and
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