REPORT ON THE RADIOLARIA. 1015 



Order VI. CYRTELLAEIA, Haeckel, 1881. 



Definition. NASSELLAKIA with a complete lattice-shell enveloping the central 

 capsule. 



Suborder I. SPYEOIDEA, Haeckel. 



Spyridina,, Ehrenberg (pro parte), 1847, Monatsber. d. k. preuss. Akad. d. 



Wiss. Berlin, p. 54. 



Zygocyrtida, Haeckel, 1862, Monogr. d. Eadiol., p. 291. 

 Zygocyrtida, Biitschli, 1882, Zeitschr. f. wiss. Zool., vol. xxxvi. p. 501. 

 Acanthodesmida, R. Hertwig, 1879, Organismus der Radiol., p. 68. 

 Spyrida vel Spyroidea, Haeckel, 1881, Prodromus, p. 440. 



Definition. NASSELLARIA with a complete lattice-shell, exhibiting constantly a 

 bilocular cephalis with a sagittal constriction. 



The suborder Spyroidea, and the two following closely allied suborders, 

 Botryodea and C y r t o i d e a, represent together that large group of Radiolaria 

 which I first described in my Monograph (1862, pp. 272, 280) as the family Cyrtida, but 

 afterwards as a separate order (or sublegion) under the name Cyrtellaria (1883, 

 Jena. Sitzungsber., Feb. 16, p. 18). This group comprises all those MONOPYLEA or 

 NASSELLAKIA which possess a complete lattice-shell, whilst the preceding P 1 e c t e 1- 

 1 a r i a never develop a perfect fenestrated shell enveloping the central capsule. The 

 Spyroidea differ from the other Cyrtellaria (Botryodea and Cyrtoidea) 

 in the bilocular shape of the cephalis, which is bisected by the sagittal ring and a 

 corresponding longitudinal constriction into two symmetrical halves. 



The Spyroidea appear in the first system of Polycystiua of Ehrenberg (1847, 

 loc. cit., pp. 53, 54) as the fourth of his seven families, under the name Spyridina, with 

 the following definition : " Testae nucleo destitutes (associates et coalitaa) ; cellulse binse 

 clathratse, nucis forma ainplse, strictura longitudinal! levius discretae." Ehrenberg united 

 them with his " Polycystina composita or SPUMELLAEIA " and separated them from the 

 closely allied " Polycystina solitaria or NASSELLARIA." He distinguished among them 

 five genera, two of which have no external appendages (Dictyospyris and Pleurospyris), 

 whilst the other three possess spiny or lamellar appendages (Ceratospyris, Cladospyris, 

 and Petalospyris). These five genera and the accompanying definitions were also 

 repeated in the same terms in the last system of Ehrenberg (1875, loc. cit., p. 157). 

 In my Monograph (1862, pp. 280, 291) the Spyroidea are enumerated as a sub- 



