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Show 456 DR. W. G. RIDEWOOD ON THE CRANIAL [Dec. 13, Clupea eprattus. There is a median fontanelle between the mesethmoid and the frontal bones. Temporal and Preopercular Series (text-fig. 123).- The posttemporal is rather large and slender. It has two long limbs attached to the epiotic and opisthotic respectively; the third limb, that which carries the sensory canal, is very short, and touches the back of the supratemporal. The supratemporal is elongated horizontally; its sensory canal, entering behind from the post-temporal, divides, as usual, into one branch going upward to the parietal and another which passes forward into the squamosal. The axis of the upright limb of the preopercular is more oblique in Clupea harengus than in Clupea Jinta, and the interopercular bone and the lower limb of the preopercular are relatively longer. Circumorbital Series (text-fig. 123).-There are eight bones of this series-a small nasal, and seven bones disposed around the eye. The orbital ring is incomplete above. Text-fig. 123. P°P wp q cui Clupea Jinta, right side of skull. For explanation of lettering see p. 493. rMaxillary Series (text-fig. 123).- The gape is bounded above by the maxilla and premaxilla, both of which bear a row of minute teeth along the lower edge. In Clupea harengus there are rarely more than three teeth in each premaxilla, but in Clupea jinta the number is between twenty and thirty. Two surmaxillary bones are present on each side. Mandibular Series (text-figs. 123 and 124, p. 457).-The mandible is rather high in proportion to its length, particularly so in Clupea harengus. In Clupea Jinta the highest point of the mandible lies |