1544 THE VOYAGE OF H.M.S. CHALLENGER. 



they are also connected at the two parapylse. The radiate operculum of the astropyle 

 opens by a tubular prolongation or proboscis, which is very long in the former, shorter in 

 the latter. The two parapylse of the latter also bear short tubules. The protoplasm, 

 enclosed in the inner membrane, contains numerous small circular vacuoles. The large 

 central nucleus is sometimes spherical or ellipsoidal, at other times spheroidal or 

 lenticular ; it always contains numerous nucleoli. One specimen observed, with two 

 nuclei, was apparently engaged in self-division (fig. 2). 



The spherical gelatinous calymma, in the centre of which the central capsule is placed, 

 has a diameter of 1 to 2 mm. In the specimen of Phceodina tripylea, which I observed 

 living, it exhibited exactly the same shape as the figure of Dictyocha stapedia in 

 PI. 101, fig. 10; the only distinction in this latter being indicated by the pileated pieces 

 of the skeleton on the surface. The jelly-sphere contained numerous roundish or globular 

 alveoles of very different sizes, and between them an areolated network of protoplasm ; 

 the latter has arisen from the outer surface of the calymma in the form of very numerous, 

 radiating, partly branched and anastomosing pseudopodia. The dark and opaque centre 

 of the jelly-sphere is filled up by the granular, blackish-brown pheeodium, which envelops 

 the oral half of the central capsule completely ; it exhibits the same characters as in all 

 the other PHJEODAKIA. 



Synopsis of the Genera of Phceodinida. 



Central capsule with a single opening (an astropyle on the oral pole), . . . 656. Pliaiocolla. 



Central capsule with three openings (an oral astropyle and two aboral parapylse), . 657. Pluvodina. 



Genus 656. Phceocolla, 1 Haeekel, 1879, Sitzungsb. med.-nat. Gesellsch. Jena, 



Dec. 12, p. 4. 



Definition. P hseodinida with a single aperture to the central capsule (an 

 astropyle with radiate operculum, placed on the oral pole of the main axis). 



The genus Phceocolla may be regarded as the simplest form of all PH^EODARIA, and 

 perhaps as the common ancestral form of this legion. It has no skeleton, and the central 

 capsule exhibits only a single aperture on one pole of the main axis. In this it agrees 

 with the Challengerida, Medusettida, and Castanellida, which have also no parapylse or 

 secondary openings. 



1. Phceocolla jyrimordialis, n. sp. (PL 101, fig. 1). 



Central capsule subspherical, or somewhat depressed in the direction of the main axis. The 

 oral pole of the latter exhibits a large astropyle, or a radiate operculum, about as broad as the 



1 PJueocolla = Brown jelly; <pio';, xo'?,x. 



