FAMILY CERATOCORYACEAE 



37 



higher epitheca, and absence of wings between the spines. 

 There is no comment on the extraordinary size, which, 

 if correctly given, would be the outstanding character- 

 istic of the species. 



The true relationships of this species cannot be de- 

 cided until the morphology is known in detail. The spe- 

 cies probably belongs to the subgenus Protoceratocorys. 

 Ceratocorys kofoidii has not been treated elsewhere in 

 this report because of the imperfect knowledge of its 

 thecal morphology. 



The present report includes seven species, three of 

 which are new. One of Kofoid's (1910) species has been 

 listed as uncertain. Furthermore, the species have 

 been arranged into two subgenera, the first attempt at a 

 subgeneric division of Ceratocorys so far made. 



Systematic Position 



Ceratocorys is probably most closely related to the 

 genus Goniodoma . This is indicated especially by the 

 number of plates in the two genera and by the patterns 

 of their ventral areas (see p. 6). 



Ceratocorys is characterized by 29 plates, the 

 smallest number found among the genera investigated in 

 this report (see p. 7). The number of epithecal plates, 

 including the apical closing platelet, is only 10; and the 

 number of hypothecal plates is only 8. There are 6 gir- 

 dle plates and only 5 sulcal plates. Goniodoma agrees 

 with Ceratocorys In all these particulars except in the 

 number of epithecal plates, this being 11 instead of 10. 



The actual relationship of these two genera is prob- 

 ably not so close as the agreement in the number of 

 plates suggests. For instance, although the number of 

 hypothecal plates is the same, the tabulation is quite 

 different: Ceratocorys has 6 postcingulars (2 of which 

 are minute), 1 small intercalary, and 1 antapical; Goni - 

 odoma has 5 postcingulars (subequal in size), no inter- 

 calaries, and 3 antapicals. 



The relationship of Ceratocorys to Goniodoma is 

 perhaps better demonstrated by the tabiilations of the 

 ventral areas, a fact particularly evident from the spe- 

 cies of Ceratocorys with a short flagellar pore, such as 

 C. armata (cf. figs. 1, 53). The pattern of Ceratocorys 

 approaches that of Goniodoma more than that of any oth- 

 er genus investigated, but differs from it in the follow- 

 ing features: in Goniodoma the sulcal ring is complete; 

 the posterior sulcal plate touches the pore; and the left 

 sulcal plate is large and forms the left side of the pore. 



The ventral areas of these two genera further agree 

 in their simplicity of contours, although in Ceratocorys 

 the area is narrower and there is a very definite depres 

 sion of the left side to form a sulcus, whereas in Gonio - 

 doma the area is almost flat and a sulcus proper is ab- 

 sent. 



In the presence of the ventral epithecal pore, Cera - 

 tocorys resembles not only Goniodoma but also Gonyau - 

 lax and other related genera. Since there seems to be no 

 uniformity among the various genera as to which plate 

 bears this pore, the position of this structure in Cerato - 

 corys may be of no value in indicating relationships. 



Ceratocorys is not closely related to any genus oth- 

 er than Goniodoma (see p. 8). 



Relationships of the Species 



In a discussion of the Interspecific relationships, 

 we have to deal with the following morphological char- 

 acters: degree of angularity of body; bipedal hypotheca; 

 number of major hypothecal plates; number of sulcal 

 plates; number of hypothecal spines; presence of dorsal 

 and ventral spines; and presence of brush spines. 



On the basis of the most fundamental of these char- 

 acters, the difference in plate pattern, we can group the 

 species into two subgenera: Protoceratocorys n.subgen. 

 and Euceratocorys n.subgen. Protoceratocorys has pol • 

 in the sulcal complex, so that there are 6 functional sul- 

 cal plates and only 5 postcingulars. Euceratocorys has 

 pol definitely in the postcingular series, so that there 

 are 5 sulcal plates and 6 postcingulars. 



Protoceratocorys includes two species: C. skogsber - 

 gii and C. gourretii . Ceratocorys skogsbergii has an an- 

 gular body and no dorsal or ventral spine; C. gourretii 

 has a rounded body and dorsal and ventral brush spines 

 as well as four antapical brush spines. It is thus evident 

 that the two species of this subgenus are distinct. 



Euceratocorys includes five species: Of these C. 

 horrida is isolated by being the only one with dorsal and 

 ventral spines, and brush spines. It is further separated 

 from the other species of the subgenus by its angular 

 body, extreme development of lists, and low epitheca. 



Ceratocorys bipes is unique in its bipedal body shape 

 and in the presence of only two antapical spines. Cera - 

 tocorys aultii is a small species with four antapical 

 spines and with body little compressed posteriorly. 

 Ceratocorys armata and C. reticulata are the only two 

 species of the genus which show close mutual relation- 

 ships. They are both compressed posteriorly and have 

 three or four antapical spines. 



The evolution in this genus, thus, has been very di- 

 vergent (see fig. 46). The ancestral form of the genus 

 probably was small, spherical, and with four simple ant- 

 apical spines. If this assumption is correct, there has 

 been, in the subgenus Protoceratocorys, the development 

 of the angular body and reduction of spines in C. skogs - 

 bergii ; on the other hand, there has been a retention of 

 the primitive body shape but development of brush and 

 dorsal and ventral spines in C. gourretii, the two spe- 

 cies having separated at an early time. 



Of the five species in the subgenus Euceratocorys, 

 C. aultii may be considered the most primitive, having 

 four antapical spines and rather rounded body. Cerato - 

 corys armata and C. reticulata have developed only in 

 size and toward a more pointed antapex. Ceratocorys 

 bipes represents a trend toward bilobed antapex and loss 

 of all but two spines, which are somewhat more devel- 

 oped than in the primitive species. Ceratocorys horri - 

 da has reached the highest development of angularity of 

 body and development of spines and Usts. It probably 

 was separated from the primitive form at an early date. 



It win be noted that the tendency to develop dorsal 

 and ventral spines is correlated with the tendency to de- 

 velop brush spines of considerable length. These devel- 

 opments occur in both subgenera: in the very small ro- 

 tund species, C. gourretii, and in the large angular spe- 

 cies, C. horrida . This must be considered convergence. 



