UNIVERSITY OF CALIFORNIA PUBLICATIONS 



IN 



ZOOLOGY 



Vol. 1 1, No. 5. pp. 89-126, pi. 2 June 21, 1913 



SAGITTA GALIFOBNICA, N. SP., FROM THE 

 SAN DIEGO REGION 



INCLUDING REMARKS ON ITS VARIATION AND 

 DISTRIBUTION 



BY 



ELLIS L. MICHAEL 



INTRODUCTION 



After publishing the results of a long and critical study of 

 the chaetognatha of the San Diego region involving the indi- 

 vidual identification of nearly 80,000 specimens, a few net-hauls 

 made in October, 1911, unexpectedly yielded what the former 

 prolonged search failed to reveal — a new species. Popping, as 

 it were, into existence so suddenly and being the only new 

 chaetognath taken from California waters, this species has 

 seemed to me to take appropriately the name, Sagitta calif arnica. 



While certain very apparent characteristics of this new 

 species seemingly make it impossible to confuse it with any other, 

 still it sometimes happens that specimens are described as con- 

 stituting a new species when the differential characteristics upon 

 which the definition is based later prove to be abnormalities or 

 extremes of variability within an old species. I have endeavored 

 to giiard against such a pitfall by making accurate diagnostic 

 measurements on as many specimens as practicable, and to this 

 end table 1 is supplied, which is based upon micrometer measure- 

 ments of fourteen structural features in each of one hundred of 

 the most perfectly preserved specimens. In addition to this the 



