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



13. Gonylaulax fragilis (Schiitt) 



PI. 15, figs. 33, 34, 36, 37; pi. 13, fig. 25. 

 Stei7iiella fragilis Schiitt (1895), pi. 6, figs. 261.14. 



Diagnosis: Length, 1.14 to 1.35 transdiameters. Epitheca 

 conical, hypotheca asymmetrically rounded, girdle displaced 3 

 girdle widths. No spines. 



Description: Body rotund, somewhat elongated, slightly flattened on 

 ventral face. Epitheca and hypotheca subequal. Epitheca a low cone, 

 0.66 transdiameters in middorsal altitude, its sides slightly convex. No 

 apical horn. Apical region extending a short distance on dorsal face. 

 Hypotheca sac-like, its middorsal altitude 0.72 transdiameter, abruptly 

 and asymmetrically rounded at antapex, the left side being a trifle the 

 fuller. Girdle slightly premedian, descending, displaced distally 3 girdle 

 widths, without overhang, proximal end curved posteriorly, furrow not 

 deeply impressed, with scarcely any salient ridges and no lists. Ventral 

 area indenting the epitheca scarcely a girdle width, widening posteriorly 

 to the right and then to the left. 



Plate formula 3', 0", 6", 6, 6'", 1p, 1"". Apical 1' slender, about 0.5 

 girdle width across, slightly sigmoid, with elongated closing platelet 

 which extends upon the dorsal face at its anterior end. It joins the 

 anterior plate of the ventral area posteriorly. Apicals 2' and 3' surround the 

 apex in saddle fashion. Precingular 6" triangular. Postcingular V" long 

 and slender, expanding anteriorly less than a girdle width across. Posterior 

 intercalary IP, two girdle widths across. Antapical 1"" deeply indented by 

 the posterior end of the ventral area. The ventral area is about 0.5 

 girdle width across between girdle ends, flaring asymmetrically pos- 

 teriorly to at least 3 girdle widths and carried well under the antapex 

 into the antapical plate, and usually without lists. The surface is nearly 

 smooth, with feeble or more pronounced vermiculations running in short, 

 sinuous longitudinal lines. They run posteriorly from the pores about 

 which they take their origin. (See Schiitt, 1895, pi. 6, fig. 26..) Often 

 two originate from the same pore. Suture bands are finely areolated. 

 The arrangement of surface markings, of pores and of chromatophores 

 all give the organism an appearance of longitudinal striation. In some 

 specimens the vermiculations coalesce (pi. 13, fig. 25) to form a semi- 

 striate meshwork with pores at the nodes. Chromatophores ellipsoidal, 

 irregular, or linear, in peripheral or radial arrangement, several large 

 anteriorly located pusules and posteriorly located ellipsoidal nucleus. 



Dimensions: Length, 82-105/x; transdiameter, 65-80/a; dorso- 

 ventral diameter, 60-65(U. ; width of furrow, 5;u,. 



Variation: I have noted some variation in form of antapex, 

 surface markings, and shape of ventral area, which is usually not 

 so wide as figured by Schiitt (1895). 



