SOME PUGET SOUND ASCIDIANS. 609 



Distaplia occidentalis Ritter (MS.). 



Distaplia occidentalis Bancroft, '99, p. 59. 



Next to Aniaroiiciinn no other genus of compound ascidians 

 is more abundantly represented, at least as to number of indi- 

 viduals, on our coast than is Distaplia. They present great va- 

 riety in form and size of colony, and in color, and I have, at va- 

 rious times and from various localities, entered provisionally in 

 my notes at least four species. These have, however, always 

 been differentiated on superficial characters, /. e., characters of 

 the colonies. The attempt to find constant structural differences 

 between the zooids of the supposed species have been unsuccess- 

 ful thus far, and as the superficial characters are found, upon ex- 

 amination of a very great quantity of material collected at different 

 seasons of the year, to be exceedingly variable and inconstant, I 

 am now of the opinion that but a single species has yet come 

 under my observation. The differences in color and form and 

 size of colony are probably due to differences in age, state of de- 

 velopment of the zooids, and perhaps of other factors not yet 

 recognized. 



The colonies contained in the present collection are somewhat 

 larger and thicker than is usual with specimens from points 

 farther south, but beyond this I find nothing distinctive in them. 



University of California, Berkeley, California, July 14, 1898. 



BIBLIOGRAPHY. 



'98, Bancroft, F. W. The Anatomy of Chelyosoma productum 

 Stimpson. 

 Proc. Cal. Acad. Sci., 3d Ser., Zooi., Vol. I., No. 8, 1898, p. 309. 



'99, Bancroft, F. W. Oogenesis in Distaplia occidentalis Ritter 



(MS.), with remarks on other species. 



Bull. Mus. Comp. Zool. Harvard Univ., 1899, Vol. XXXV, pp. 

 59-112. 



'84, Drasche, Richard von. Ueber einige neue und weniger ge- 



kannte aussereuropaische einfache Ascidien. 



Denksch. der kaiserlichen Akad. der Wissensch. zu Wien, Math. 

 Naturw. Classe, 48 Bd., 1884, p. 369. 



