A treatise on zoology . Osteichthyes are included in this thehighest Order of fish. The typical Teleostei are characterised bycertain modifications of which the chief are the following: the lossof the ganoine covering the exoskeleton ; the rounded thin over-lapping scales; the simple annular or amphicoelous bony vertebral TELEOSTEI 345 centra; the intermusculjii- bones ; the homocercal tail with hypiiialbones; the further reduction of the radials of the paired fins; thespine-like postclavicle ; the supraoccipital (p. 326); the unpairedvomer; the simplification of the lower jaw, which loses the
A treatise on zoology . Osteichthyes are included in this thehighest Order of fish. The typical Teleostei are characterised bycertain modifications of which the chief are the following: the lossof the ganoine covering the exoskeleton ; the rounded thin over-lapping scales; the simple annular or amphicoelous bony vertebral TELEOSTEI 345 centra; the intermusculjii- bones ; the homocercal tail with hypiiialbones; the further reduction of the radials of the paired fins; thespine-like postclavicle ; the supraoccipital (p. 326); the unpairedvomer; the simplification of the lower jaw, which loses the supra-angular and splenial, preserving only the dentary angular andarticular; the absence of special cheek-plates, and loss of themedian gular; the median urohyal; the reduction of the conusand its valves, and compensating development of the truncusarteriosus ; the loss of the optic chiasma and of the spiral valve ;the special vas deferens, and ovarian sac. Many of these characters are not possessed by the lower forms,. prth ecar sm Fio. 3-2d. Right-side view of the skull of Slopsmnrus, h. (From Ridewood, Proc. Zool. .Sot-.) cor, cir-cumorbitals; d, dentary; ecar, devniarticular; /, frontal; hm, hyomandibular; iop, inter-opercular ; inx, maxilla ; n, nasal; opo, opercular; pm, premaxilla ; pop, preopercnlar; pt, iwst-temporal; q, quadrate ; sm, svipramaxillaries ; sop, subopercular ; st, snprateinporals. either becaiise the new structures have not yet become developedor because certain ancestral characters are not yet lost. TheTeleostei are the most recent of all the Actinopterygian Orders ;.they are not known to occur below the Jurassic, and thus offer tothe systematist at once the best opportunity for tracing outphylogeny, and a most confusing number of intermediate the most recent advances in the classification we are chieflyindebted to Gill [165], Giinther [191-92], Sagemehl [379], Jordan[250-51], A. 8. AVoodward [505], and Boulenger [40-42]. In the skull we noti
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Keywords: ., bookcentury1900, bookdecade1900, bookpublishe, booksubjectzoology
