REPORT ON THE RADIOLARIA. 1157 



Genus 510. Archibursa, 1 Haeckel, 1881, Prodromus, p. 429. 



Definition. A rchiperida (vel Monocyrtida triradiata clausa) without internal 

 columella and without apical horn. 



The genus Archibursa has probably arisen from Peridium by loss of the apical 

 horn, and is the only genus of Archiperida which bears no horn. The three basal feet 

 are well-developed. It differs from the similar Tristylospyris by the absence of the 

 sagittal ring and the corresponding longitudinal constriction. 



1. Archibursa tripodiscus, n. sp. (PI. 98,. fig. 6). 



Shell subspherical, smooth, with irregular roundish pores. Basal plate with Miree large 

 triangular pores of equal size (fig. 6). Three feet widely divergent, straight, three-sided prismatic, 

 about as long as the diameter of the shell. 



Dimensions. Diameter of the shell 0'07,. length of the feet 0'09.. 



Habitat.- Central Pacific, Station 272, depth 2600 fathoms. 



Family LX. PH^NOCALPIDA, n. fam, 



Arcliiphormida et Archiphcenida, Haeckel, 1881, Prodromus, pp. 428, 429. 



Definition. M onocyrtida multiradiata. (Cyrtoidea with a simple, not 

 jointed shell, resembling a simple cephalis, with numerous radial apophyses (four to nine 

 or more). 



The family Phsenocalpida, composed of the Archiphormida and Archiphsenida of 

 my Prodromus, comprises those Cyrtoidea in which the lattice-shell is quite without 

 transverse constriction, but bears numerous radial apophyses. The two subfamilies 

 differ in the shape of the basal mouth, which in the Archiphormida is a simple wide 

 opening, but is closed in the Archiphsenida by a lattice -plate. 



Several Phsenocalpida were formerly described by Ehrenberg, viz., Halicalyptra 

 virginica (in 1844) and Litharachnium arachnodiscus (in 1872, called by him 

 Carpocanium, though it is quite different from this genus, and closely allied to my 

 Litharachnium tentorium, figured in 1862). These forms belong to the Archiphormida 

 (with open mouth). Several fossil Archiphsenida (with closed mouth) were figured by 

 Ehrenberg, in 1875, as belonging to Petalospyris (ocellata, carinata, flabellum}, though 

 the absence of the sagittal ring and the corresponding longitudinal constriction 

 demonstrates their character as Phcenocalpis. 



1 Archibursa = Primordial bottle ; 



