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



Subgenus 2. Amphibelithium, Haeckel. 



Definition. All twenty spines grown together in the centre, forming a single 

 star-shaped piece of acanthin. 



5. Amphibelone clavaria, n. sp. 



Two principal spines roundish, without edges and wings ; the smaller frontal spine elongate 

 conical, the larger caudal spine two to four tunes as long, cylindrical, in the distal part spindle- 

 shaped or club-shaped, with conical apex. Central base simple pyramidal, without leaf-cross. 

 Eighteen smaller spines much shorter, bristle-shaped. Central capsule very long, club-shaped. 

 All twenty spines perfectly grown together in the centre. 



Dimensions. Length of the frontal spine 0'12, of the caudal spine 0'4 to O'S ; frontal breadth 

 O'Ol, caudal breadth 0'03 ; length of the eighteen smaller spines 0'05. 



Habitat. Central Pacific, Station 272, surface. 



Genus 343. Acantholonche, 1 Haeckel, 1881, Prodromus, p. 4G6. 



Definition. A mphilonchida with two equal principal spines (frontal and 

 caudal spines not different). The eighteen smaller spines are very unequal, ten of them 

 (eight tropical and two transverse equatorial spines) much larger than the rudimentary 

 eight polar spines. 



The genus Acantholonche differs from its ancestral genus Amphilonche in the 

 different shape of the eight tropical and the eight polar spines ; these latter are much 

 smaller than the former, which are almost equal to the two transverse equatorial spines. 

 The two principal spines are equal, but in size and shape very different from the 

 others. 



1. Acantholonche amphipolams, n. sp. (PL 132, fig. 7). 



Two principal spines stout, quadrangular prismatic in the basal half, cylindrical or spindle- 

 shaped in the distal half, with simple conical apex ; base a small pyramid without leaf-cross. 

 Two transverse and eight tropical spines, about half as long as the former, very thin, bristle-sbaped, 

 conical at the basal part. Eight polar spines very small, scarcely one-eighth or one-fourth as long 

 as the latter, short pyramidal or conical, often quite rudimentary. Central capsule cylindrical, 

 enveloping the basal half of the two principal spines. 



Dimensions. Length of the two principal spines 0'4 to 0'5, of the ten smaller spines 0'2 

 to 0'3, of the eight rudimentary polar spines O'Ol to 0'06 ; breadth of the two large spines 0'02 

 to 0-03. 



Habitat. Central Pacific, Stations 266 to 274, surface. 



1 Acant'iolonche = Spiny epear ; xxatSa., Ao'yxi- 



