KOFOID AND RIGDEN: SCHIZOGONY IN GONYAULAX. 341 



in Ceratium which bears certain resemblances to the type of repro- 

 duction here described. His outline drawings unfortunately afford 

 no critical evidence of the precise skeletal relations of the two cells. 

 In the case of Ceratium described by him the budding cell arises by 

 nuclear division, one sister apparently retaining the whole parental 

 skeleton and the other and smaller one seemingly forming an entirely 

 new theca. The resemblances in this phenomenon to that here 

 described lie in the formation of an entire new theca on the "bud" 

 and in the initial difference in size in two daughter cells in Ceratium 

 which is comparable with the underlying inequality in division which 

 has given rise to the Gonyaulax chain. The marked differences be- 

 tween the two lie in well-defined chain formation in Gonyaulax series, 

 while in the budding Ceratium it is not conclusively evident either 

 from Apstein's text or his figures that this process of budding ever 

 leads to chain formation, while, if his interpretation of "abgefallene 

 Knospen" be correct chain formation following budding must be 

 at the best exceedingly rare. As a result protoplasmic continuity 

 is absent and skeletal completeness upon the bud is possible. There 

 is also in the Gonyaulax chain, as found, no such marked contrast 

 between the "bud" and its sister cell in the matter of size and skele- 

 ton as appears in budding Ceratium. 



The organism here dealt with is not assignable to any described 

 Dinoflagellate and its full thecal structure is so imperfectly revealed 

 or developed that a full determination of its position and relationships 

 is impossible. Some clues as to its affinities are suggested by the 

 plates as developed. The hypotheca is that of Gonyaulax, with one 

 antapical, Y", one posterior intercalary, l p , and 6 postcingulars, 1'"— 

 6'", of which V" is a small plate. These same features pertain to 

 the hypotheca in certain other genera, Amphidoma, Ceratocorys, 

 and Steiniella. In Amphidoma the girdle is not displaced; it is in 

 all species of Gonyaulax. In Ceratocorys there are but four pre- 

 cingulars; in Gonyaulax there are six as here. In Steiniella there 

 are in all known species peculiar vermiculate surface markings, and 

 an apical closing platelet is peculiarly elongated; both of these 

 features are lacking or less prominent in Gonyaulax. In this species 

 the surface is unmarked and the apex indeterminable. In view of 

 the evident close relationships of Gonyaulax and Steiniella and the 

 absence of decisive characters leading toward the latter genus it seems 

 best to assign this species provisionally to Gonyaulax pending the dis- 

 covery of the full complement of plates. 1 



In a recent paper (Univ. Calif. Publ. Zool., v. 8) the senior author has reduced 

 Steiniella to a subgenus of Gonyaulax. 



