No. I.] THE EMBRYOLOGY OF CREPIDULA. 7 



lection of eggs and embryos of C. adunca, a species quite com- 

 mon on the Pacific coast. I have made a brief study of the 

 embryology of this form. The peculiar features in its develop- 

 ment will be referred to later. During the course of this work 

 I have also studied, more or less carefully, the embryology of 

 several other genera of marine prosobranchs, viz., Urosalpinx 

 cinerea, Fulgur carica, Sycotypus canaliculatus, lUyonassa 

 obsoleta, Tritia trivittata, Neverita duplicata. 



If space and opportunity permitted, it would be a pleasure 

 to mention the names of many friends who in one way or 

 another have assisted me, but I cannot fail to speak of two or 

 three persons who have placed me under very great obligations. 

 I am indebted to Professor C. O. Whitman, Director of the 

 Marine Biological Laboratory, for the opportunity of working 

 at that excellent institution, as well as for many stimulating 

 suggestions and friendly criticisms ; to Professor W. K. Brooks, 

 my former instructor, for valuable assistance during the first 

 year of my work ; and particularly am I indebted to my wife, 

 who has finished from my camera sketches many of the draw- 

 ings which illustrate this paper, and has in many other ways 

 rendered me great assistance. 



2. Methods?- 



The ova were fixed in many different fluids, — Kleinenberg's 

 picro-sulphuric, picric acid in sea water, Perenyi's, Flemming's 

 stronger and weaker, Merkel's, Auerbach's, Hermann's, cor- 

 rosive sublimate, chromo-formic, chromo-acetic and absolute 

 alcohol ; but for surface views of the entire o^g^ none of these 

 methods for a moment compares with the first named, i.e., 

 Kleinenberg's stronger picro-sulphuric. The ova were left in 

 this for a length of time varying from fifteen to thirty minutes, 

 and were then gradually transferred to 70 % alcohol. . They 

 were left in this until all traces of picric acid had been washed 

 out, and were finally preserved in 95 % alcohol, 



1 The substance of this section was published in the American Naturalist, vol. 

 XXVII {1893). 



