1150 THE VOYAGE OF H.M.S. CHALLENGER. 



irregularly ramified and tapering towards the distal end. (Similar to Clathrocorys teuscheri, PL 64, 

 fig. 10, but with four free spines, without connecting lattice- wings.) 



Dimensions. Shell 0'07 long, O06 broad ; horn and feet 0'2 to 0'25 long. 



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



6. Cladoscenium pectinatum, n. sp. (PI. 98, fig. 2). 



Shell subspherical, with irregular roundish pores. Basal plate with three large holes. 

 Oolumella with two verticils of three ascending lateral branches. Apical horn and the three feet 

 of nearly the same size and form, three to four times as long as the columella, straight, three- 

 sided prismatic, each with five to eight verticils of three simple lateral branches, tapering towards 

 the distal end. 



Dimensions. Shell 0'07 long, 0'08 broad ; horn and feet 016 to 0'22 long. 



Habitat. South Atlantic, Station 332, depth 2200 fathoms. 



Genus 506. Archiscenium? HaeckeL, 1881, Prodromus, p. 429. 



Definition. A rchiperida (vel Monocyrtida triradiata clausa) with a free 

 simple internal columella, prolonged into an apical horn. Three basal feet connected 

 with the horn by three vertical lateral wings. 



The genus Archiscenium and the following nearly allied Pteroscenium are derived 

 from the two preceding genera, from which they differ in the development of three free 

 vertical lateral lattice-wings ; these arise from the upper edge of the three basal feet 

 and connect them with the three edges of the apical horn. The basal part of the latter, 

 enclosed in the shell, forms an internal free columella, which in Archiscenium is simple, 

 not branched. 



1. Archiscenium quadrispinum, n. sp. (PI. 53, fig. 11). 



Shell hemispherical, smooth, with a small number of large irregular polygonal meshes and thin 

 bars. Basal lattice with three very large central meshes and six smaller peripheral meshes (two on 

 the base of each foot). Apical horn and the three feet of equal size and similar form, slender, 

 pyramidal, widely divergent, straight, as long as the shell-diameter. Three lateral wings small, 

 little prominent, each with two or three irregular meshes. Central capsule subspherical. 



Dimensions. Shell 0'05 long, 01 broad. 



Habitat. Central Pacific, Station 274, depth 2750 fathoms. 



2. Archiscenium clathrocorys, n. sp. 



Shell campanulate, smooth, with numerous irregular square meshes. Basal lattice with three very 

 large meshes. Apical horn and the three feet of equal size and similar form, three-sided prismatic, 



1 A rchiscenium = Primordial tent ; 



