UNIVERSITY OF CALIFORNIA PUBLICATIONS 



IN 



ZOOLOGY 



Vol. 9, No. 2, pp. 85-104, pis. 10-12 December 28, 191 1 



ON A LYMPHOID STRUCTURE LYING 



OVER THE MYELENCEPHALON 



OF LEPISOSTEUS 



BY 



*4 



ASA C. CHANDLER 



CONTENTS 



PAGE 



Introduction 85 



Occurrence and homologies 87 



In genus Lepiftosteus 87 



Absence in other Ganoids 87 



Possible homology with ' ' Saccus endolymphaticus ' ' in Protopterus 88 



General morphology 88 



Histology 90 



Development 93 



18-22 mm. stages 93 



55 mm. stage 94 



Summary 95 



Literature cited 97 



INTRODUCTION 



The present paper is a preliminary report on a peculiar 

 gland-like, lymphoid structure discovered over the myelence- 

 phalon of Lepisostcus while dissecting out the brain in the labor- 

 atory of Professor B. G. Wilder, at Cornell University, during 

 the fall of 1910. The work was begun in Cornell University 

 during the college year 1910-11, and later carried on in the 

 Zoological Laboratory at the University of California. 



Grateful acknowledgments are here made to Professors C. A. 

 Kofoid and J. Frank Daniel, of the University of California, 







A Thesis submitted to the Department of 

 Zoologj'- in partial fulfillment of the require- 

 ments for the degree of Master of Science- in 

 the College of Natural Sciences, of t he- 

 University of California, May. 1912. 



