Page:Scientific results HMS Challenger vol 18 part 2.djvu/139

Rh

Definition.— with a complete lattice-shell enveloping the central capsule.

Spyridina, Ehrenberg (pro parte), 1847, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 54. Zygocyrtida, Haeckel, 1862, Monogr. d. Radiol., p. 291. Zygocyrtida, Bütschli, 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.— with a complete lattice-shell, exhibiting constantly a bilocular cephalis with a sagittal constriction.

The suborder, and the two following closely allied suborders, and , 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  (1883, Jena. Sitzungsber., Feb. 16, p. 18). This group comprises all those or  which possess a complete lattice-shell, whilst the preceding  never develop a perfect fenestrated shell enveloping the central capsule. The differ from the other  ( and ) in the bilocular shape of the cephalis, which is bisected by the sagittal ring and a corresponding longitudinal constriction into two symmetrical halves.

The appear in the first system of Polycystina of Ehrenberg (1847, loc. cit., pp. 53, 54) as the fourth of his seven families, under the name Spyridina, with the following definition:—"Testæ nucleo destitutæ (associatæ et coalitæ); cellulæ binæ clathratæ, nucis forma amplæ, strictura longitudinali levius discretæ." Ehrenberg united them with his "Polycystina composita or " and separated them from the closely allied "Polycystina solitaria or ." 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 are enumerated as a