A treatise on zoology . Fig. 301a. Ksox bwius, L. A, two radials of the dorsal fin,.,, , 1 ^, left-side view. B, radial and dermal ray from in rays still greatly exceed the front, a, distal cartilage ; m, median segment, and haemal arches in number ^^^T^inT °^ ?^ = lepidotrich. 322 HOLOSTEI (Figs. 62-3). The lepidotrichia can be erected aud depressed in allthe fins except the caudal (Fig. 301 a). The median radials pro-ject not at all beyond the level of the body-wall, and are composedof three-jointed rods as a rule ; the proximal segment is long (inter-spinous bone), the two distal segments s
A treatise on zoology . Fig. 301a. Ksox bwius, L. A, two radials of the dorsal fin,.,, , 1 ^, left-side view. B, radial and dermal ray from in rays still greatly exceed the front, a, distal cartilage ; m, median segment, and haemal arches in number ^^^T^inT °^ ?^ = lepidotrich. 322 HOLOSTEI (Figs. 62-3). The lepidotrichia can be erected aud depressed in allthe fins except the caudal (Fig. 301 a). The median radials pro-ject not at all beyond the level of the body-wall, and are composedof three-jointed rods as a rule ; the proximal segment is long (inter-spinous bone), the two distal segments short, the outer one beingrigidly fixed in the bifurcated base of the lepidotrich. The tailis abbreviate heterocercal, homocercal, or of some more modifiedtype (p. 353); but the hinder end of the iipper lobe of the hetero-cercal tail of the larva (the axial lobe) is always lost during. Fig. 302. Skull of SaZmo saZnc, L., cut longitudinally. (After Bruch.) a, angular ; al, alisphenoid ;or, articular ; Ijo, basioccipital; hsp, baslsplienoid ; d, dentary; , ethmoid cartilage; mo,exoccipital; A, hyomaudibular; li, ligament; , Meckels cartilage; ?npj, metapterygoid ;7»y)f, mesopterygoid ; Hia;, maxilla ; osp, orbitosphenoid ; j), post-temporal; p«, palatine; pmsc,preinaxilla; -pro, prootic ; ps, parasplieroid; ipt, i)terygoid ; q, quadrate ; so, supraoccipital;sih, stylohyal ; S)/, syinplectic; vo, vomer. development, and the notochord does not reach the extremity ofthe tail in the adult. Therefore the adult caudal fin is formedchiefly from the hypochordal lobe, but also to a small extent fromthe epichordal lobe (Fig. 46). The radials of the paired fins arestill more i-educed than in the Chondrostei. The clavicle is lost,its place being taken by the cleithrum, and the endoskeletal pectoralgirdle is relativeh small (Fig. 241). The maxilla generally bothacquires
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Keywords: ., bookcentury1900, bookdecade1900, bookpublishe, booksubjectzoology
