EEPORT ON THE RADIOLAEIA. 681 



3. Cuhotholus rhomhicus, n. sp. 



Surface of the shell smooth. Both principal cupolas (on the poles of the longitudinal axis) 

 larger than the two lateral (on the poles of the transverse axis), and these larger than the two 

 sagittal cupolas (on the poles of the sagittal axis). Therefore all three fundamental axes unequal. 

 Pores irregular, roundish, twice to four times as broad as the bars ; eight to twelve in the basal 

 semicircle of each cupola. Medullary shell lentelliptical. 



Dimensions. — Major (principal) axis 0'16, middle (lateral) axis 0'14, minor (sagittal) axis 0'12 ; 

 pores 0-006 to 0-012, bars 0-003. 



Habitat. — South Atlantic, Station 335, depth 1425 fathoms. 



Subgenus 2. Cuhotholura, Haeckel. 

 Definition. — Sui-f;xce of the shell with radial spines or thorns. 



4. Cuhotholus octoceras, n. sp. 



All six cupolas in pairs of different sizes. Both principal domes larger than the lateral domes, 

 and these larger than the sagittal domes. Pores subregrilar, circular, twice as broad as the bars ; 

 eii^ht to ten in the semicircle of each cupola. From the sm-face arise (at the intersecting points of 

 every three cupolas) eight strong conical radial spines, about as long as the shell-axis ; they lie in two 

 diagonal planes, and are the external free prolongations of eight inner beams (homologous with the 

 eio-ht wino--spines of Tdraiyylc odacantha), which connect the lentelliptical medullary shell with 

 the eight corners of the cuboidal central chamber. 



Dimensions. — Major axis of the cortical shell 0-15, middle 0-13, minor O'll ; pores O'OOS, 

 bars 0-004 ; diameters of the medullary shell corresponding to 0-05, 004, 0-03. 



Habitat. — ^Western Tropical Pacific, Station 224, depth 1850 fathoms. 



Genus 300. Ciibotholonium,^ n. gen. 



Definition. — Tholonida with double (or sometimes triple) cortical shell (with 

 external veil), composed of six hemispherical cupolas, opposite in pairs on the poles of 

 three axes perpendicular one to another, covering six sides of the cuboidal Larnacilla- 

 shaped central chamber (with medullary shell). 



The genus Cuhotholonium differs from the nearly allied Cuhotholus (its probable 

 ancestral form) only in duplication of the cortical shell. I have observed only two 

 species of this rare form, both rather different. In the first species the outer cortical 

 shell forms a simple spherical thin veil around the inner, the six cupolas of which are 

 nearly of the same form and size. In the second species each of the domes of the 



1 Cubotholcmium = ^VD.&\\ shell with cupolas disposed ou the six sides of a cube ; xi//3o;, dohuviov. 

 (ZOOL. CHALL. ESP. — PART XL. — 1885.) Rr 8G 



