File:A treatise on zoology (1900) (14760329746).jpg

Identifier: treatiseonzoolo09lank (find matches)
Title: A treatise on zoology
Year: 1900 (1900s)
Authors: Lankester, E. Ray (Edwin Ray), Sir, 1847-1929 Bather, Francis Arthur, 1863-1934 Goodrich, Edwin S. (Edwin Stephen), 1868-1946
Subjects: Zoology
Publisher: London : A. & C. Black
Contributing Library: Robarts - University of Toronto
Digitizing Sponsor: University of Toronto

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(168), Cori (93), Julin, Dohrn). Soon thislatter vein breaks up in the liver into the hepatic portal capillarysystem, its anterior portion forming the hepatic veins. Theinferior jugulars are replaced by a median inferior jugular belowthe ventral aorta. This vein, and a ventral hepatic vein, arepeculiar to the Cyclostomes (Fig. 18). The two anterior and alsothe posterior cardinals join above the oesophagus to large trunks,which open to the right into the dorsal limb of the sinus venosus.The ductus Cuvieri on the left side thus disappears, and all thevenous blood pours into the heart on the right side. In theMyxinoidea, strangely enough, it is the left ductus which persists,and the right ductus which is suppressed (Figs. 32, 34). The pronephros nearly disappears in the adult Lamprey, butpersists as an organ of considerable size in Myxinoids (Fig. 27).It is, however, degenerate (Weldon (483), Semon (400), Kirkaldy(263a)), consisting of a few branching tubules, o— le one 44 CYCLOSTOMATA
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Fig. 27. Myxine glutinosa, L. A, ventral view of a dissection ; 8, cartilage near the opening of the right gill-pouches (indicated by dotted line): C, similar cartilage on the left side. a,c, abdominal coelom, exposed by cutting way ventral body-wall; af, afferent vessel; b.d, hile-duct cut short; bt, branchial tube leading to exterior) c, cartilage ; c.b.w, cut body-wall; g.l, gill-lamellae exposed in grill-sac ; go, branchial opening; g.s, gill-sac; i, intestine opened up; i.v, dotted line indicating course of portal vein: k, kidney-duets o.b, bile-duet opening ; o.d, oesophageal duct; p, pharynx opened; pc, poricardiun opened, the heart has been removed p.h, portal heart; p.l, left. posterior cardinal vein: p.o, opening from pericardial into abdominal coelom; pr, pronephros, with funnels on its surface ; r.pr, dotted line indicating hidden right pronephros ; s.v, sinus venosus cut across; v, portal vein; v.a, ventral aorta, the afferent vessels have been cut short on lie left side, and the heart cut off behind the conus.

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