EEPORT ON THE RADIOLARIA. 975 



(in the figure seen from the apical pole) with cylindrical rods, armed with numerous stout spines, 

 branched like a deer's antler. Basal gate rather oblong, twice as broad as long. 



Dimensions. — Height of the frontal ring 008, breadth 016. 



EaUtat. — Central Pacific, Station 272, depth 2600 fathoms. 



4. Coronidium acacia, n. sp. (PI. 82, fig. 2). 



Frontal ring and sagittal ring nearly circular, of equal size, truncated at the base. Basal ring 

 circular, somewhat smaller. All three rings with prominent edges, bearing bunches of short and 

 straight pointed spines, like those of an Acacia. Basal gate circular. 



Dimensions. — Height of the frontal rin" 0'12, breadth 0'14. 



Habitat. — Tropical Atlantic, Station 348, depth 2450 fathoms. 



Genus 417. Acanthodesmia,^ J. Miiller, 1856, Monatsber. d. k. preuss. 

 Akad. d. Wiss. Berlin, p. 485. 



Definition. — Coronida with five large, partly latticed gates (four lateral and one 

 basal). Skeleton composed of two incomplete, partly fenestrated meridional rings, and 

 one complete basal ring. 



The genus Acanthodesmia, the oldest known form of all Coronida, differs fi-om the 

 preceding Coronidium, its ancestral form, in the development of nregular loose lattice- 

 work along the rings, and therefore bears to it the same relation that Zygostephanium 

 does to Zygostephanus. The first species described by Johannes Miiller, Acantho- 

 desmia vinculata ("with five large gates between the bars of the shell") remains the 

 true type of this genus ; the second species described by him (Acanthodesmia dumetum) 

 belongs to the Plectanida [Polyplecta). 



1. Acanthodesmia vincidata, J. Miiller. 



Acanthodesmia vinculata, J. Miiller, 1858, Abhandl. d. k. Akad. d. Wiss. Berlin, p. 30, Taf. i. 



figs. 4-6 (non 7). 

 Lithocircus vincukdus, J. Miiller, 1856, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 484. 



Frontal ring \iolin-shaped, one and a half times as broad as high, with a sagittal constriction. 

 Sagittal ring ovate, smaller. The four gates between the two rings are partly fenestrated by a few 

 thin threads, irregularly branched and connecting the two rings. A few short thorns are scattered 

 here and there. Basal gate elliptical. 



Dimensions. — Height of the frontal ring 012, breadth 0'18. 



Habitat. — Mediterranean (Nice), Atlantic (Canary Islands), surface. 



1 Acanthodesmia = Thorn-band ; oLkx-jScc, "iicfuoi. 



