REPORT ON THE RADIOLARIA. 1523 



figures of new PH^EODARIA, the names of which (as found by me in 1879 in the corres- 

 ponding preparations) are the following ; (l) Challengeria naresii, (2) Challengeria 

 aldrichii, (3) Bivalva compressa (now = Conchopsis compressa), (4) Tuscarora 

 belknapii, (5)' Challengeria circopora (now= Circoporus sexfurcus), and (6) Haeckeliana 

 porcellana. A great number of these Challengerida (twenty species) were afterwards 

 figured by Dr. John Murray in the Narrative of the Cruise of H.M.S. Challenger, 

 1885, vol. i. part 1, p. 226, PL A ; viz., fourteen species of Challengeria and six species 

 of Tuscarora. 



The most important advance in the knowledge which we had of the peculiar 

 organisation of the PH^EODARIA, was made by the accurate description which Richard 

 Hertwig published, in 1879, of the intimate structure of their central capsule, and mainly 

 of its peculiar openings. He examined living at Messina the following three forms, 

 described in my Monograph; (l) Aulacantha scolymantha, (2) Aulosphwra elegantis- 

 sima, and (3) Ccelodendrum. ramosissimum. Besides, he described an interesting new 

 genus, Caelacantha anchorata; and another new form, which he placed in the 

 Aulosphaerida, as Aulosphcera gracilis, but which really was a new genus of Sagos- 

 phserida, here described as Sagoscena gracilis. Finally, Hertwig first discovered that 

 the peculiar bodies, described by Ehrenberg as Dictyocha and placed by him in the 

 Diatomea (Polygastrica), were the isolated pieces of the skeleton of a true Pheeodarium, 

 and that they were scattered loosely in great numbers over the surface of the jelly -sphere, 

 just as are the hollow spicula of Thalassoplancta or Cannobelos. 



The six species mentioned, of which Hertwig gave a very accurate description and 

 very instructive figures, belong to six different genera, and these represent six different 

 families of PH/EODARIA, viz. ; Aulacanthida, Aulosphserida, Ccelodendrida, Cannosphserida, 

 Sagosphserida and Cannorrhaphida. He found that all these six forms, in spite of great 

 differences in the form and structure of their skeleton, were identical in the structure 

 of the central capsule ; and since he observed constantly three openings in its double 

 wall (a large main-opening on the oral pole, and a pair of lateral accessory openings on the 

 aboral pole of its main axis) he called them TRIPYLEA (loc. cit., p. 87, 94). But he also 

 pointed out the remarkable shape of their voluminous extracapsular body, and especially 

 the characteristic position, size, colour and composition of the large pigment body, which 

 I had called the phseodium. 



The accurate description of the gigantic and elegant skeleton of a new Pheeodarium, 

 surpassing all other known Radiolaria in its extraordinary size (15 mm.), was published in 

 1882 by 0. Biitschli (in Zeitschr. f. wiss. Zool., vol. xxxvi. p. 486, Taf. xxxi.). He called 

 , it Ccelothamnus davidoffii, in honour of its discoverer, who had found it floating on the 

 surface of the Gulf of Villafranca, near Nice. He placed it among the Ccelodendrida ; it 

 belongs, however, to that part of this group which possesses a nasal tube, and which I 

 afterwards separated under the name Coelographida, 



