REPORT ON THE RADIOLA.RIA. 731 



Actinastrum pentazonium (p. 733) and of Chiastolus amphicopium (PI. 129, fig. 3), but much more 

 numerous, smaller, and not regularly disposed. These latter two Actinelida must be separated 

 on account of the regular disposition of the thirty-two spines. 



Dimensions. Length of the spines O2, basal breadth O'OOS, distal breadth 0'02. 



Habitat. South Pacific, Station 165, surface. 



Subgenus 3. Actinelonium, Haeckel. 



Definition. Radial spines quadrangular, prismatic, or pyramidal, their transverse 

 section square. 



4. Actinelius pallidus, Haeckel. 



Actinelius pallidus, Haeckel, 1865, Zeitschr. f. wiss. Zool., Bd. xv. p. 364. 



Spines eighty to one hundred and twenty or more, quadrangular, prismatic, of equal breadth 

 throughout their whole length. Apex simple, truncate or pyramidal. Base a four-sided slender 

 pyramid. Central capsule pale yellowish. Granules of the sarcode colourless. 



Dimensions. Length of the spines 0'2 to 0'3, breadth 0'005. 



Habitat. Cosmopolitan ; Mediterranean, Atlantic, Pacific. 



5. Actinelius poly acanthus, n. sp. 



Spines two hundred to three hundred or more, quadrangular, pyramidal, gradually thinned 

 towards the simple apex. Base a small three-sided pyramid. Central capsule opaque. 

 Dimensions. Length of the spines 012 to 018, basal breadth 0'012. 

 Habitat. South Pacific, Station 291, surface. 



Genus 318. Astrolophus, 1 Haeckel, 1881, Prodromus, p. 469. 



Definition. A strolophida with a variable and undetermined number of 

 simple radial spines of different sizes (large and small spines intermingled), which are 

 united in the centre of the spherical central capsule. 



The genus Astrolophus differs from the nearly allied ancestral genus Actinelius 

 only in the unequal size of the numerous radial spines. In both observed species very 

 numerous small spines are intermingled with a small number of large spines, and 

 between them numerous spines of medium size. The small spines fill up the hollow 

 spaces between the basal parts of the large spines. 



1 Astrolophus=Ste.T-lik.e bunch ; 



