1911] K of oid: The Genus Gonyaulax. 211 



apical-preeingular suture. PrecinguJar 1" is vertically displaced anteriorly 

 the whole length of 6", separated by ventral area from plate 6", which 

 is nearly triangular (pi. 10, fig. 10). Postcingular 1"' is very small, 

 linear, overhanging oblique part of ventral area. Posterior intercalary is 

 1 to 1.3 girdle widths across. 



The plates of the ventral area (v. a., pi. 10. fig. 8) are much obscured 

 by the obliquity and overhang of the girdle. The anterior plate (ant. pi.) 

 slightly indents the epitheca, is not crossed by the anterior girdle ridge 

 and bears on its postmargin the anterior edge of the flagellar pore. The 

 intermediate plates (int. pi., pi. 10, fig. 10) must be small as they are 

 more or less hidden in the oblique part of the longitudinal furrow. The 

 posterior plate (post, pi.) is large and extends anteriorly almost to the 

 level of the distal end of the jjosterior girdle ridge. Its posterior end 

 roundly indents the antapical plate. 



The surface is smooth, sparingly porulate with large pores, especially 

 near suture lines which are marked by faint lines. A faint reticulum 

 about the pores is sometimes developed. Eidges along girdle and ventral 

 area heavier, continued on either side in short spinules which are rather 

 nearer together than in G. digitale, being about 1.5 girdle widths apart. 

 Often but a single spine, the right one, is present, and sometimes none 

 at all is found. In the brackish water form of this species described as 

 G. levanderi, Paulsen (1907, fig. Sa), has figured these spines as postero- 

 dorsal to the end of the ventral area and also finds several small acces- 

 sory spinules. The two spines in our material are located near the points 

 where the ventral area indents the antapical, a position which the anta- 

 pical spines often occupy in this genus. Lists on the spines are rare in 

 this species. Chromatophores often dark yellowish brown. Contents 

 dense, occasionally pale and translucent. 



Dimensions: Length, 24 to 50ju„ generally 35 to 40/x; trans- 

 diameter, 21 to 38/x. In the Aral Sea Ostenfeld (19C8) records 

 forms referable tentatively to this species, 40 to SO/x in length 

 and 32 to 44/* wide. A few of our marine forms approaching 

 this size have been found by me. 



The following table of measurements gives the range in 

 dimensions observed in San Diego material and recorded else- 

 where. 



Measurements of GonijeiuJa.r spinifera 

 (Dimensions in Microns) 



Trans- 

 Locality Date Length diameter 



San Pedro Harbor, Calif., May 31, 1901 44 35 



San Pedro Harbor, Calif., May 31, 1901 35 31 



San Pedro Harbor, Calif., May 31, 1901 40 35 



San Pedro Harbor, Calif., May 31, 1901 45 39 



Oflf San Diego, Calif., June 28, 1904 ;.... 48 37 



Off San Diego, Calif., June 28, 1904 41 23 



