A treatise on zoology . Fig. 214. Dorsal view of tlie brain ofProtopterus annectens, Owen.(After Burckhardt, from ^ooto(?i/.) 1, spinal cord:2, root of first spinalnerve; 3, diverticula of 4, thesaccus endolymphaticus ; 5,medulla oblongata; 6, fourthventricle ; 7, cerebellum ; 8,mesencei>halon (fused opticlobes); 9, stalk of pineal body ;10, thalamenceplialon ; 11, velumtransversum; 12, pineal body; 13,lobus hippocampi; 14, choroidjilexus ; 15, cerebral hemisphere(proscnccplwlon); 10, olfactorylobe. !46 DIPNOI compound nature is lost in recent Dipnoi; but in the early fo
A treatise on zoology . Fig. 214. Dorsal view of tlie brain ofProtopterus annectens, Owen.(After Burckhardt, from ^ooto(?i/.) 1, spinal cord:2, root of first spinalnerve; 3, diverticula of 4, thesaccus endolymphaticus ; 5,medulla oblongata; 6, fourthventricle ; 7, cerebellum ; 8,mesencei>halon (fused opticlobes); 9, stalk of pineal body ;10, thalamenceplialon ; 11, velumtransversum; 12, pineal body; 13,lobus hippocampi; 14, choroidjilexus ; 15, cerebral hemisphere(proscnccplwlon); 10, olfactorylobe. !46 DIPNOI compound nature is lost in recent Dipnoi; but in the early fossilsthe ridges are set with conical tubercles (Fig. 2 10a); and in. b ^ fn ^ rt R ^ O ^ n ^ Ci r - ^j tr ^- ca - =. to .- cS - --^ -^ £ 3 - K O i 5 ~;. „ some, such as Uronennis and perhaps ConrlioiMma (Traquair [458]),the separate conical teeth are not fused even in the adult. Much GILLS 247 smaller compound vomerine teeth are set on the ethmoid cartilageill front. Tlie} probably drop otF in fossils, where they have neveractually been found. The pharynx leads into an oesophagus, stomach, and straightintestine, fastened by an incomplete ventral as well as dorsalmesentery. A well-developed spiral valve is present (Giinther [190],Parker [324], Hyrtl [232]). The cloaca receives the anal, genital,and urinary openings. Paired abdominal pores are present. Ceratodus has five open branchial slits. The first, behind thehyoid arch, has a hyoidean hemibranch. It is a pseudobranchsupplied indirectly from the first epibranchial artery (Spencer [413],
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Keywords: ., bookcentury1900, bookdecade1900, bookpublishe, booksubjectzoology
