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



arm. Patagium incomplete, enveloping only the basal half of the arms as a cii-cular spongy disk of 

 loose framework. 



Dimensions. — Eadius of the arms OlS, basal breadth 0"05, distal breadth 0'08. 



Habitat. — Fossil in the Tertiary rocks of Sicily, Grotte, Stohr. 



8. Dictyocoryne echinata, n. sp. 



Arms unequal and at different distances, club-shaped, in the distal half twice as broad as in the 

 basal lialf, three times as long as the small triangular central disk, at their distal end armed with one 

 larger and several smaller conical spines. Both paired arms with touching bases, and only half as 

 large as the doubly remote odd arm. Patagium incomplete, enveloping only the basal half of the 

 arms, and forming a circular disk of looser framework. Surface thorny. 



Dimensions — -Eadius of the arms 0"15 to 0-2, basal breadth 0'03, distal breadth 0"06. 



Habitat. — South Atlantic, Station 325, surface. 



Genus 264. <Spo?i(/asienscMs/ Haeckel, 1862, Monogr. d. Radiol., p. 474 {sensu resti'icto). 



Definition. — Spo n go dis cida with four spongy arms on the margin of the 

 circular or quadrangular disk, crossed in two equatorial diameters, without a connecting 

 patagium. 



The genus Spongasteriscus (in the restricted definition here stated) exhibits on the 

 margin of the disk four spongy arms, which form either a regular or a bilateral cross. 

 It corresponds to Stauralastrum and Myelastrum among the Porodiscida, to Astractura 

 among the Coccodiscida. 



Subgenus 1. Spongasteriscinus, Haeckel. 



Definition. — Cross formed by the four arms regular, rectangular, with equal-sized 

 and equidistant arms. 



1. Spongasteriscus ovatus, n. sp. 



Arms at equal distances, forming a regu^lar, rectangular cross, egg-shaped, with a broader rounded 

 distal end, one and a thii'd times as long as broad, and three times as long as the radius of the 

 central disk ; in the latter three to four concentric rings. 



Dimensions. — Eadius of the arms 01, greatest breadth 0'06. 



Habitat. — Western Tropical Pacific, Station 225. 



1 iSponjfasiertscMS= Spongy star ; n'^oy/o;, duTi^icKo;. 



