UNIVERSITY OF CALIFORNIA PUBLICATIONS 

 ZOOLOGY 



Vol. 1, No. 3, pp. 115-156, Pis. 12-15 June 12, 1903 



EMBRYOLOGY AND EMBRYONIC FISSION 

 IN THE GENUS CRISIA.* 



BY 

 ALICE ROBERTSON. 



INTRODUCTION. 



The processes of embryonic fission in the Cyclostomata were 

 first made known a few years ago by Dr. Sidney F. Harmer. 

 That investigator found that this unique process of reproduction 

 of the embryo occurs in several somewhat distantly related genera 

 of the subclass, viz.. in Crista, in Lichenopora, and in Tubulipora. 

 The facts disclosed were so interesting and remarkable, that 

 further study of the phenomena was deemed desirable, both 

 for the corroboration of the results, and for the purpose of com- 

 pleting more of the details. The investigation reported in the 

 following pages has been made upon Crisia only, several species 

 of which occur abundantly in the vicinity of San Francisco Bay. 

 The chief results of Dr. Harmer's investigations, that is, the 

 discovery of the occurrence in this genus of a budding of 

 the embryo, the separation of the buds from the mother 

 embi-yo, and their ultimate transformation into free swimming- 

 larva 3 , have been fully con firmed. Besides as thorough a study 

 as possible has been made of the origin of the genital products, 

 both male and female. Some unique features have been found 

 in the origin and development of these elements, all of which 

 may be interpreted as secondary modifications due to the high 

 degree of colonial specialization to which these brvozoa have 

 attained. 



'Dissertation presented to tin- Faculty of the Collegeof Natural Sciences of the 



University of California in partial fulfillment of the requirement for the Degree 

 of Doctor of Philosophy. 



Zooi..— 9 [115] 



