178 University of California Publications in Zoology. [Vol. 6 



use tlic literature in connection with the material. Species 

 belonging to it have been placed in genera so widely divergent 

 in skeletal morphology as Dinophysis, Phalacroma, and Gonio- 

 dVma, and on the other hand a species has been attributed to it 

 which is a Gonyaulax, belonging to a different subfamily. 



This confusion has resulted in part from the convergence in 

 external form and superficial facies largely due to the outgrowth, 

 or to the reduction, of spines and fins in the different species in 

 certain fashions probably related to common seeds of orientation 

 and flotation. This convergence is exemplified in the superficial 

 resemblances which Ceratocorys jourdani bears to Dinophysis and 

 Phalacroma. In both the well-developed girdle-lists are placed 

 anteriorly, and compensating outgrowths at the posterior end in 

 the form of spines are of assistance in orientation and are found 

 near the sagittal plane on the posterior end of P. jourdani some- 

 what as in Phalacroma, though their relation to each other and 

 to the general skeletal morphology is quite different. This 

 superficial resemblance doubtless led Gourret (1883) to place 

 C. jourdani in the genus Dinophysis and Schiitt (1895) to retain 

 it in the family Dinophysidae though transferring it to the genus 

 Phalacroma. It is, however, utterly different in its skeletal 

 morphology and location of the fission plane from any of the 

 Dinophysidae. This same convergence later led Entz (1902) into 

 the error of maintaining that Phalacroma jourdani is a connect- 

 ing link between the two families Dinophysidae and Peridinidae, 

 and to the proposal of a new nomenclatural anomaly of "Phala- 

 croma-Ceratocorys" as the designation for these supposed 

 "Uebergangsformen." In reality all of his intermediate forms, 

 as figured, can not be distinguished from true Ceratocorys 

 jourdani, and his discussion contains no critical evidence from 

 careful analysis of skeletal morphology to justify his conclusion 

 of continuity of the two genera. 



The superficial resemblance which Ceratocorys armatum ami 

 C. bipes bear to Coniodoma is due largely to the general form of 

 the body as seen in the location of the girdle, the somewhat 

 angular contour, especially of the epitheca, the coarse pitting of 

 the shell, and the heavy rugosities on its surface near sutures. 

 These superficial features, combined with the absence of spines 



