CONCLUSIONS. 109 



CONCLUSIONS ON THE AMBLYOPSID. 



1. Amblyopsis speldus is found from Mammoth Cave north to Michigan. It is the only 



blind species occurring on both sides of the Ohio. 



2. No direct comparison of specimens from south and north of the Ohio has been made. 



3. There are 3 species of T vphlifli 111 ys occurring in 3 different localities, one of them north 



of the Ohio. 



4. Troglichthvs is confined to the caves of southwestern Missouri. 



5. The 3 species of Chologasler are found in 3 disconnected areas. 



6. The color pattern of Chologaster is controlled by the underlying musculature. 



7. Amblyopsis has been permanently bleached so that even individuals reared in the light 



do not acquire color. Its colorless condition is due to the transmission of the environ- 

 mental adaptation in past generations of cave-dwellers. 



8. Respiration is probably in part carried on through the skin. 



9. Amblyopsis is a bottom and pelagic (ubiquitous) feeder on living, moving animals. 



10. Chologasler does not depend upon its eyes for detecting and securing prey, or for avoiding 



a rod held in the hand. 



11. Amblyopsis is negatively phototactic. It seeks the dark regardless of the direction or 



wave length of the rays of light. 



12. In well-lighted, open pools Amblyopsis hides under rocks during daylight. 



13. Chologaster when deprived of its eyes is negatively phototactic, and positively stereotropic. 



They are positively tropic to red as against other rays of the spectrum. 



14. Amblyopsis probably breeds during the entire year, but more individuals carry developing 



eggs between March and May. 



15. Amblyopsis is not viviparous, but the eggs to the number of about 70 are carried in the gill 



chamber of the female from fertilization till the larvae are about 10 mm. long. The 

 eggs hatch in about a month, having a length of about 5 mm. 



16. There are few, if any, secondary sexual characters which argues in favor of the origin of 



these through sexual selection as against Geddes and Thompson's explanation that they 

 are the result of maleness. 



17. In newly hatched Amblyopsis the anus is in the normal position, behind the ventrals. 



When the fish reaches a length of 25 mm., the anus has reached a point in front of the 

 ventrals; when 10 mm. longer, the anus has moved forward to between the bases of the 

 pectorals. In mature specimens it lies anterior to this point. 



18. The heads of the Amblyopsida; are provided with tactile ridges, rows of tactile organs 



regularly and definitely arranged. 



19. These fishes are not keener in perceiving vibrations than other fishes. They may have 



greater power of discrimination between vibrations. 



20. The ear of the Amblyopsis is normally developed. These fishes do not " hear" in the 



ordinary sense of the word. 



21. The external peculiarities of the brain of Amblyopsis are the absence of optic nerve and 



chiasma; the hemispheres are relatively larger than in other fishes and the optic 

 lobes are much smaller. 



22. The dorsal walls of the optic lobes have only half the normal thickness, the differences 



being due to (a) the atrophy of the second layer; (b) the outer part of the fourth 

 layer has disappeared; (c) the descending fibers of the fifth layer are wholly wanting; 

 (</) the granular layer is thinner than normal and the ependyma is thinner and has 

 fewer cells; (e) the optic tracts are wanting. 



