670 THE AMERICAN NATURALIST. [Vor. XXXIV. 
turned so as to compensate in a measure for the abnormal position 
in which the fish is placed. Lee showed that these compensatory 
movements may be called forth by stimulating the sense organs of 
the semicircular canals in a quiet dogfish resting in a normal position, 
and he therefore believed that the normal compensatory movements 
of the eye were reflexes produced by a stimulation of the organs of 
the semicircular canals. E. P. Lyon! has made the interesting dis- 
covery that certain eye movements can be produced without the inter- 
vention of the semicircular canals. If the tail of a dogfish is turned 
to one side, the eye of the same side is directed forward, that of the 
opposite side, backward. As this experiment succeeds after the 
eighth nerves are cut, it follows that this reflex is not to be regarded 
as originating in the ear. Moreover, when the spinal cord is divided 
well forward in the body, the reflex ceases, and the author, therefore, 
rightly concludes that the sensory disturbances, which give rise to 
the reflex, are located in the posterior part of the trunk and make 
their way forward through the cord. The author finally calls atten- 
tion to the uncertainty of compensatory movements of the eye as 
evidence of stimulation of the organs in the semicircular canals. 
y 
Development of Lepidosiren. — The development of this rare and 
interesting fish is being worked out by J. Graham Kerr,? whose first 
paper on the subject gives an account of the way in which eggs may 
be obtained and the external features of their development. The 
eggs are laid in underground burrows in swamps. The fertilized egg 
as taken from the nest is enclosed in a thin, horny capsule, round 
which is occasionally a jelly-like envelope. Segmentation is com- 
plete and unequal, as in Amia. The gastrula closely resembles that 
of Petromyzon. The medullary folds are low, and the neural axis 
arises mainly as a solid down-growth. There is no neurenteric 
canal. Four external gills are developed upon branchial arches, I, 
II, III, and IV. Auditory and nasal sacs and stomodzum are 
formed by secondary excavation of originally solid rudiments. The 
young fish, which at hatching is tadpole-like, remains two weeks 
without developing pigment, after which the retinal pigment begins 
1 Lyon, E. P. Compensatory Motions in Fishes, Amer. Journ. of Phys. vol. iv 
(1900), pp. 77-82. TES 
2 Kerr, J. Graham. The External Features in the Development of Lepidos 
paradoxa Fitz, Phil. Trans. Roy. Soc. London, Ser. B, vol. cxcii (1900), pp- 2997 
330, Pls. VIII-XII. 
