REPORT ON THE RADIOLARIA. 967 



anterior larger pectoral, and two posterior smaller tergal feet). This species may be regarded as a 

 commencing Hcxaspyris or Liriosjnjris. 



Dimensions. — Height of the sagittal ring 0"08, breadtli 0'06. 



Habitat. — Central Pacific, Station 271, depth 2425 fathoms. 



3. Semantiscus hexajyylus, n. sp. (PI. 92, fig. 17). 



Sagittal ring ovate, thorny, with a small apical horn. Basal ring with six roundish or nearly 

 triangular gates ; the two jugular pores are smaller than the two cardinal and larger than the two 

 cervical pores. The separating bars between these six pores are prolonged into six straight, thorny 

 widely divergent feet ; three larger feet (the caudal and the two pectoral) with a pair of apophyses 

 three smaller between them simple (the sternal and the two tergal feet). 



DimcTisions. — Height of the sagittal ring 0"1.3, breadth 0'09. 



HabUat. — Western Tropical Pacific, Station 225, depth 4475 fathoms. 



Family L. Cokonida, Haeckel. 



TriostepMda, Haeckel, 1881, Prodromus, p. 445. 



Definition. — S tephoidea with tw^o crossed vertical rings, perpendicular one to 

 the other (the primary sagittal and the secondary frontal ring). Usually their 

 common base bears a horizontal basal ring, but a mitral ring (or a horizontal ring at 

 the apex) is never developed. 



The family Coronida comprises those Stephoidea in which the primary 

 sagittal ring (of the Stephanida and Semantida) becomes crossed by a second vertical 

 ring, the lateral or frontal ring. Between these two vertical meridian rings, perpen- 

 dicular to one another, four large apertures remain constantly open, the " lateral " gates. 

 But besides these four constant openings, usually (excepting only in the Zygo- 

 stephanida) other gates are developed on the common base of the two crossed rings, 

 produced by a third, horizontal, basal ring. These basal gates are the same which we 

 have found already in the Semantida. 



The distinction of the Coronida from the other Stephoidea is always easy. In 

 the Stephanida and Semantida, the frontal ring, or the second meridian ring, which 

 we find in all Coronida, is never developed. On the other hand these latter never 

 exhibit the tj^iical "mitral ring," or the second, upper, horizontal ring, which 

 distinguishes the Tympanida. 



We distinguish here, among the Coronida, four different subfamilies, which perhaps 

 afterwards may be better separated as families. Of these four groups the Zygo- 

 stephanida and Acanthodesmida exhibit the nearest relationship to the Stephanida, 

 whilst the Eucoronida and Trissocyclida possess a closer affinity with the Semantida. 



