74 IOWA ACADEMY OF SCIENCES. 



men this supposed growth is really taking place, and at 

 each end the bone for a short distance is imbedded in 

 cartilage. 



LITERATURE. 



Cope, E. D. — Structure and Affinities of the Amphiumidae. Proc. 

 Amer. Philos. Soc, 1886. 



Batrachia of North America. Bull. No. 3i, U. S. Nat. Mus., 1889. 



Hay, O. P. — The Skeletal Anatomy of Amphiuma, during its earlier 

 stages. Jour. Morph. Vol. IV, 1890. 



Kingsbury, B. F. — The Lateral Line System of Sense Organs in some 

 American Amphibia, and Comparison with Dipnoans. Proc. Amer. Micros. 

 Soc. Vol. XVII, 1895. 



Kingsley, J. S. — The Head of an Embryo Amphiuma. Amer. Nat. 1892. 



Wiedersheim, R. — Das Kopfskelet der Urodelen. Morph. Jahrb. Bd. 

 Ill, 1877. 



Wilder, H. H. — Die Nasengegend von Menopoma alleghaniense und 

 Amphiuma tridactylum. Zool. Jahrb. Bd. V., 1892. 



Winslow, G. M. — The Chondrocranium in the Ichthyopsida. Tuft's Col- 

 lege Studies, No. 5, 1898. 



THE SOLAR SURFACE DURING THE PAST TWELVE 

 YEARS— A REVIEW OF SUN-SPOT OBSERVA- 

 TIONS MADE AT ALTA, IOWA, FROM 



1890 TO 1902. 



BT DAVID E. HADDEN. 



The following paper is a resume of a series of sun-spot 

 observations commenced b}^ the writer in lvS90, August 1st, 

 and continued without interruption, except by cloudy 

 weather and other unavoidable causes — such as sickness or 

 absence from the city — until the present time. 



Embracing, as it does, the most interesting period of a 

 sun-spot cycle — that of a maximum of solar activity, 

 included between two minima — it is hoped that a study of 

 the results may be of interest and value to students, and a 

 contribution to the literature of solar physics. 



The principal instrument used w^as a 3-inch telescope 

 until 1S97, February, after which time a 4-inch telescope. 



