366 



University of California Puhlications in Zoology. [Vol.4 



Species of Ceratium. 



Total 



32 



85 



19 



125 



These belonged to 21 species, of which 15 were represented in 

 part or wholly by normal individuals, that is by those in which 

 neither autotomy nor regeneration, either with or without pre- 

 ceding autotomy, was evident. In species of the C. tripos group 

 autotomy is revealed by the opened tips. In species of the C. 

 macroceros group, carriense, deflea>um, intermedium, longipes, 

 protuberans, tenuissimum and vultur, which normally have open 

 tips, autotomy is only made evident when the arms are appreciab- 

 ly shortened by the process. The detection of individuals in 

 which autotomy had occurred in these species is therefore a mat- 

 ter of judgment and liable to error or prejudice especially in 

 cases approaching the norm of the species. My judgment as to 

 the norm is based upon my impressions after some years of ex- 

 perience in examination of these species and upon the records 

 of many measurements and comparisons with many camera draw- 

 ings. 



