REPORT ON THE RADIOLARIA. 1545 



nucleus. From its centre arises a conical nianiniilla, prolonged into a thin, cylindrical, S-like lubulus, 

 the proboscis, which is about as long as the diameter of the capsule. The outer membrane of the 

 capsule is thick and double-contoured; the inner is very tliin, but distinct, and includes finely 

 graniilated protoplasm, and numerous spherical, clear vacuoles, each with some small granules. 

 . Nucleus spheroidal, depressed in the direction of the main axis, containing numerous dark, irregularly 

 ■ amcebiform nucleoli. The diameter of the nucleus is about equal to the radius of the central capsule. 

 The extracapsular calymma is an alveolated sphere, the diameter of which is six to eight times that 

 of the capsule. The inner part of it contains an irregular, l)lackish plia'odium, which surrounds and 

 hides the oral half of the central capsule. 



Dimensions. — Diameter of the central capsule OIG, of the nucleus 0'08, of the calymma 

 1-0 to 1-2. 



Habitat. — Central Pacific, Station 271 to 274, surface. 



Geuu.s 657. PhcBodina,^ Haeckel, 1879, Sitzungsb. med.-nat. Gesellsch. Jena, 



Dec. 12, p. 4. 



Definition. — P hseodinida with three apertures to the central capsule (an astropyle 

 on the oral pole of the main axis, and two lateral parapylse on both sides of the aboral 

 pole). 



The genus Plueodina has the same structure of the central capsule as the majority of 

 Ph.eodaria ; one large main-opening or astroj^yle on the oral pole of the main axis, and 

 two smaller lateral accessory openings or parapylse on each side of the aboral pole : it is 

 therefore a true Tripylean genus, like the majority of Ph^odaria. 



1. PliCBodina tripylea, Haeckel (PI. 101, fig. 2). 



? Tripylea sp., E. Hertwig, 1879, Organismus d. Radiol., Taf. x. figs. 1, 11. 



Central capsule spheroidal or lenticular, somewhat depressed in the direction of the main axis. 

 Astropyle with a strongly ribbed, radiate operculum, scarcely one-third as broad as the diameter of 

 the capsule, and prolonged into a short tubular proboscis. Parapylse also with short tubular openings. 

 The outer strong (double-contoured) membrane of the central capsule is separated from the inner 

 thin (simple-contoured) membrane by a wide interval, filled up by a clear fluid or jelly ; only at 

 the three apertures both membranes are in direct connection. The granulated protoplasm contains 

 numerous vacuoles, and surrounds a large spheroidal nucleus, with numerous small nucleoli. The 

 voluminous calymma in a specimen, observed living, was alveolar, and the ramification of the 

 pseudopodia, as well as the formation of the dark brown phaeodium, very similar to that of 

 Bictjjocha stapedia (PI. 101, fig. 10). Another specimen, figured in PI. 101, fig. 2, exhibited the first 

 stages of self-division ; the reticulated nucleus and the radiate operculum of the astropyle were 

 already doubled, and the two membranes of the capsule between them constricted in the median 

 plane. To this species belong probably the two centi'al capsules figured by E. Hertwig, loc. cit. 



1 Plueodina = Provided with brown pigment ; (paiuoiou. 



(ZOOL. CUALL. EXP. — PART XL. — 1886.) Er 194 



