6 The Ganoids 



"In addition to these, so to speak, purely embryonic char- 

 acters there are not a few important adult characters : 



" (i) The continuity of the oviducts with the genital glands. 



" (2) The small size of the pancreas, and the presence of 

 numerous so-called pancreatic caeca. 



" (3) The somewhat coiled small intestine. 



" (4) Certain characters of the brain, e.g., the large size of 

 the cerebellum; the presence of the so-called lobi inferiores 

 on the infundibulum, and of tori semi-circulares in the mid- 

 brain. 



" In spite of the undoubtedly important list of features to 

 which we have just called attention, a list containing not less 

 important characters, both embryological and adult, separating 

 Lepidosteus from the Teleostei, can be drawn up: ^ 



" (i) The character of the truncus arteriosus. 



" (2) The fact of the genital ducts joining the ureters. 



" (3) The presence of vasa efferentia in the male carrying 

 the semen from the testes to the kidney, and through the tubules 

 of the latter into the kidney-duct. 



" (4) The presence of a well-developed opercular gill. 



"(5) The presence of a spiral valve; though this character 

 may possibly break down with the extension of our knowledge. 



" (6) The typical Ganoid characters of the thalamencephalon 

 and the cerebral hemispheres. 



" (7) The chiasma of the optic nerves. 



"(8) The absence. of a pecten, and presence of a vascular 

 membrane between the vitreous humor and the retina. 



" (9) The opisthoccelous form of the vertebrae. 



" (10) The articulation of the ventral parts of the haemal 

 arches of the tail with the processes of the vertebral column. 



"(n) The absence of a division of the muscles into dorso- 

 lateral and ventro-lateral divisions. 



"(12) The complete segmentation of the ovum. 



"The list just given appears to us sufficient to demonstrate 

 that Lepidosteus cannot be classed with the Teleostei; and we 

 hold that Miiller's view is correct, according to which Lepi- 

 dosteus is a true Ganoid. 



"The existence of the Ganoids as a distinct group has, how- 

 ever, recently been challenged by so distinguished an ichthy- 



