REPORT ON THE RADIOLARIA. 579 



Genus 254. Spongophacus? Haeckel, 1881, Prodromus, p. 461. 



Definition. S pongodiscida with a simple circular disk, without radial append- 

 ages, on the margin surrounded by a thin porous or solid equatorial girdle. 



The genus Spongophacus, represented hitherto only by a single but interesting 

 species, differs from Spongodiscus by the peculiar girdle which surrounds the margin of 

 the disk in the equatorial plane. It simulates the same formation as Perichlamydium 

 in the Porodiscida, and resembles also Periphoena, &c., in the Phacodiscida. 



1. Spongophacus periphcena, n. sp. 



Spongy disk lenticular, with an irregular, dense framework, in the centre darker than in the 

 peripheral part. Margin of the disk very thin, surrounded by a broad, circular girdle, lying in 

 the equatorial plane, about as broad as the half radius of the spongy disk. The inner part of the 

 girdle is perforated by numerous irregular, small pores, which pass over gradually into the spongy 

 meshes ; the outer part is quite homogeneous, solid, transparent, with an extremely thin margin. 



Dimensions. Diameter of the disk 0'2 ; breadth of the girdle 0'05. 



Habitat. Pacific, central area, Station 271, depth 2425 fathoms. 



Subfamily 2. SPONGOTROCHIDA, Haeckel, 1881, Prodromus, p. 461. 



Definition. S pongodiscida with a circular disk, the margin of which is armed 

 with solid radial spines, situated in the equatorial plane (rarely also on both sides of 

 the disk with radial spines). 



Genus 255. Spongolonche,' 1 ' Haeckel, 1881, Prodromus, p. 461. 



Definition. S pongodiscida with two solid marginal spines, opposite in one 

 equatorial diameter of the disk. 



The genus Spongolonche opens the series of the Spongotrochida, or of those 

 Spongodiscida in which the margin of the disk is armed with solid radial spines, 

 situated in the equatorial plane. Spongolonche possesses only two such spines, opposite 

 in one equatorial diameter of the disk ; it corresponds therefore to Stylocyclia among 

 the Coccodiscida, to Xiphodictya among the Porodiscida. 



1 Spongophaciis = Spongy lens ; 



2 Spongolonche = Spongj disk with spontoons ; 



