. Bulletin of the British Museum (Natural History) Zoology. Fig. 7. Tilapia guinasana. Rugose ornamentation on the right frontal in the area between the origin of the frontal's contribution to the frontoparietal crest and the supraorbital opening of the cephalic lateral-line system. Specimen as in Fig. 5B. Magnification x Fig. 8. Tilapia guinasana. Posteromedian area of the frontals to show their ornamentation. The ridge situated over and partly anterior to the laterosensory canal opening into the infraorbital canal (see this page) is clearly visible on the left frontal. Immediately anter
. Bulletin of the British Museum (Natural History) Zoology. Fig. 7. Tilapia guinasana. Rugose ornamentation on the right frontal in the area between the origin of the frontal's contribution to the frontoparietal crest and the supraorbital opening of the cephalic lateral-line system. Specimen as in Fig. 5B. Magnification x Fig. 8. Tilapia guinasana. Posteromedian area of the frontals to show their ornamentation. The ridge situated over and partly anterior to the laterosensory canal opening into the infraorbital canal (see this page) is clearly visible on the left frontal. Immediately anterior to this ridge, part of the compact superficial layer of bone has been removed to reveal the spongy bone (arrow A) intercalated between the upper and lower layers of compact bone. Skull orientated so that the vomer points to twelve o'clock. Specimen as in Fig. 5B. Magnification x 12. however, show any inflation of its frontals). Except in the largest skull there is little development of the median frontal crest formed along the suture line between the left and right bones and which continues forward the antero- dorsal outline of the supraoccipital crest. Even in the largest T. guinasana skull the crest is relatively lower than that in comparable-sized neurocrania of other Tilapia species, espe- cially T. sparrmanii (Fig. 5). A reduction of the crest's height in small specimens, relative to that in larger ones, is, how- ever, a feature of all the small T. sparrmanii skulls examined (the only species for which an adequate growth series was available). Another unusual and probably unique feature of the fron- tal in T. guinasana is the development of an obvious, some- times prominent, and slightly curved ridge running on or a little anterior to the passage through that bone of the lateral-line tubule opening into the infraorbital canal series (Fig. 8). The ridge originates on the frontal below and contiguous with the frontal portion of the fronto-parietal crest slightly anterior
Size: 1813px × 1378px
Photo credit: © Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookcollection, bookpublisherlondonbutterworths
