A treatise on zoology . Fk;. 63. Dissected tail of Sahno. (After,Kolliker.) c, centrum of caudal vertebra ; ef, epichordaldermal ray ; , haemal arch ; , hypochordal fin ; hp, ex-panded haemal arch or liypural; i,dermal ray of opposite (right) side; , neural spine; nt, upturned extremity of thenotochord ; 2>l, covering bony plate (modified neural arch ?). TAIL 103 This ventral lobe is invariably supported by single rigid skeletalpieces, the haemal arches. Some traces of subdivision may befound in Elasmobranchs, and distal nodules of cartilage may bepresent in these and other fish
A treatise on zoology . Fk;. 63. Dissected tail of Sahno. (After,Kolliker.) c, centrum of caudal vertebra ; ef, epichordaldermal ray ; , haemal arch ; , hypochordal fin ; hp, ex-panded haemal arch or liypural; i,dermal ray of opposite (right) side; , neural spine; nt, upturned extremity of thenotochord ; 2>l, covering bony plate (modified neural arch ?). TAIL 103 This ventral lobe is invariably supported by single rigid skeletalpieces, the haemal arches. Some traces of subdivision may befound in Elasmobranchs, and distal nodules of cartilage may bepresent in these and other fish ; but it is still an open question. V^ M. A ,L. (After Lotz.) B, tail of Pne/iromi^/^e(pn(rHSAo show n. the last external trace 6f the heterocereal structure, a bony she_ath of tip ofnotochonl «^ scales covering the upturned tip of notochord ; rf dorsal (?) ;<?.?, dorsarobe rf ypochordal fin ; /, fulcra; /I, hypural bone ; /..«, haemal arch ; , neural arch andspine ; , vertebral centrum ; , ventral lobe of hypochordal hn. whether the radials have fused with the arches, are represented bythe nodules, or are altogether absent (Fig. 46). Doubtless the notochordal axis primitively extended in astraight line to the extremity of the tail, as it still does in Cyclo-stomes and Cephalochordates. The median fin fold probablystretched continuously along the dorsal edge to the tip of the tail,and a^ain ventrally from the tip to near the anus (p. 71). Butsuch a simple structure is rarely if ever found in either living or I04 PISCES -hF. extinct Pisces. It is generally repr
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