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MESSRS. F. M. BALFOUR AND W. N. PARKER ON THE 
Ganoids, and which., in the absence of evidence to the contrary, must still be assumed 
to be true for all Ganoids except Lepidosteus, is a secondary arrangement. This con¬ 
clusion follows from the fact that in Eiasmobranchs, &c., which are not descendants of 
the Ganoids, the same arrangement of seminal ducts is found as in Lepidosteus, and it 
must therefore have been inherited from an ancestor common to the two groups. 
If, therefore, the current statements about the generative ducts of Ganoids are true, 
the males must have lost their vasa efferentia, and the function of vas deferens must 
have been taken by the homologue of the oviduct, presumably present in the male. 
The Teleostei must, moreover, have sprung from Ganoid ei in which the vasa efferentia 
had become aborted. 
Considerable phylogenetic difficulties as to the relationships of Ganoidei and Elasmo- 
branchli are removed by the discovery that Ganoids were originally provided with a 
system of vasa efferentia like that of Elasmobranchii. 
The Alimentary Canal and its Appendages. 
I.— Anatomy. 
Agassiz (No. 2) gives a short description with a figure of the viscera of Lepidosteus 
as a whole. Van der Hceven has also given a figure of them in his memoir on the 
air-bladder of this form (No. 8), and Johannes Muller first detected the spiral valve 
and gave a short account of it in his memoir (No. 13). Stannius, again, makes 
several references to the viscera of Lepidosteus in his anatomy of the Vertebrata, 
and throws some doubt on Muller's determination of the spiral valve. 
The following description refers to a female Lepidosteus of 100*5 centims. (Plate 27, 
fig. fi6). 
With reference to the mouth and pharynx, we have nothing special to remark. 
Immediately behind the pharynx there comes an elongated tube, which is not 
divisable into stomach and oesophagus, and may be called the stomach (st.). It is 
about 44*6 centims. long, and gradually narrows from the middle towards the hinder 
or pyloric extremity. It runs straight backwards for the greater part of its length, 
the last 3*8 centims., however, taking a sudden bend forwards. For about half its 
length the walls are thin, and the mucous membrane is smooth ; in the posterior half 
the walls are thick, and the mucous membrane is raised into numerous longitudinal 
ridges. The peculiar glandular structure of the epithelium of this part in the embryo 
is shown in Plate 27, fig. 62 (st). Its opening into the duodenium is provided with a 
very distinct pyloric valve (py.). This valve projects into a kind of chamber, freely 
communicating with the duodenum, and containing four large pits (o'.), into each of 
which a group of pyloric caeca opens. These caeca form a fairly compact gland (c.) 
about 6*5 centims. long, which overlaps the stomach anteriorly, and the duodenum 
posteriorly. 
