216 University of California Publications in Zoology. [Vol.8 



terior girdle ridge and several intermediate {int. pi.) ones liidden in the 

 <tompressed longitudinal furrow. 



The f-Airface of northern forms (Faeroes, pi. 9, figs. 1-3, 5) is deeply 

 and coarsely reticulate with central pores in the mesh, 4 to 6 meshes on 

 the side of a precingular plate. Ribs are faintly or strongly marked along 

 sutures and those adjacent to both furrows bear lists which along the 

 girdle are ribbed. Two stout subequal antapical spines 1 to 1.5 girdle 

 widths in length and about 2 apart are often provided with fins which 

 may bear accessory spinules. In some cases these (pi. 9, fig. 4) become 

 as large as the two main spines. In exceedingly rugose individuals 

 (pi. 9, fig. 5), the fin and spines (ant. .s/j.) are converted into a recticulate 

 structure resembling the thecal wall. 



Dimensions: Length (37) 50-7 o^n; transdiameter, 3J— 50/x; 

 width of girdle, 5/^; length of antapical spines, 3 to lO/x. 



Table of ^leasnrements of Gonyaulax diyitaJe 



Length in microns 

 Locality Date excluding spines Widtli 



Faeroe Channel August. 1907 42 35 



Faeroe Channel August. 1907 57 48 



Faeroe Channel August, 1907 68 48 



Faeroe Channel August. 1907 52 43 



Faeroe Channel August, 1907 37 30 



Faeroe Channel August, 1907 40 37 



Faeroe Channel August. 1907 53 45 



Faeroe Channel August, 1907 56 48 



Faeroe Channel August, 1907 54 44 



Faeroe Channel August, 1907 67 60 



Bay of Naples April 4, 1909 60 48 



Off San Diego June 22. 1905 60 50 



Loring, Alaska Sept. 15, 1905 42 35 



Loring, Alaska Sept. 15, 1905 43 35 



Loring. Alaska Sept. 15, 1905 40 35 



Variation : Varies principally in surface markings from 

 •excessively rugose to nearly smooth forms, in the overhang and 

 displacement of the girdle, and overgrowth of the longitudinal 

 furrow by its lateral walls which is much greater in rugose speci- 

 mens, in the development of spines and fins, and in size (37-75/x). 



Comparisons: See G. spinifcra. The wide heavy form (com- 

 pare, pi. 9, fig. 2) figured by Van Breeman (1905, fig. 10b) prob- 

 ably represents a condition brought about by an expansion at 

 the apical-precingular sutures possibly preparatory to fission. 



Alaskan forms (pi. 9, fig. 4) are smaller, more rotund and 

 less rugose than those from the Faeroes. 



