REPORT ON THE RADIOLARIA. 1547 



alveolar calymma and by a voluminous mass of blackish-brown pigment, the phseodium ; 

 numerous, long, hollow, cylindrical tubes were scattered on the surface of the calymma. 

 At that time I did not know the tripylean character of the central capsule and the peculiar 

 radiate operculum in the PHyEODARiA, and therefore placed Thallassoplancta cavispicula 

 among the Thalassosphserida. 



The second description of a complete form of Cannorrhaphida was given in 1879 by 

 R. Hertwig, under the name Dictyocha fibula (Organismus d. Radiol., p. 89, Taf. ix. fig. 5). 

 The genus Dictyocha had been already founded by Ehrenberg in 1838, with the following 

 definition : " Lorica simplex, univalvis, silicea, laxe reticulata aut stellata " (Abhandl. 

 d. k. Akad. d. Wiss. Berlin, 1838, p. 128). Ehrenberg had found only scattered pieces 

 of the skeleton, fossil in Tertiary rocks. He placed them among the Bacillaria 

 ( = Diatomaceas), but added, that they may be possibly scattered spicula of Sponges 

 (" forsan Spongiarum ossicula "). 



In 1859 I myself observed similar forms of Dictyocha at Messina, and first recog- 

 nised them as true Radiolaria. But I placed them at that time among the Acantho- 

 desmida, beside Prismatium, supposing that a small spherical body which I had some- 

 times seen in the cavity of the pileated pieces (probably a phaeodellum) was the small 

 central capsule (Monogr. d. Radiol., 1862, p. 271, Taf. xii. figs. 3-6). The complete 

 body of Dictyocha was not described till 1879, when R. Hertwig gave a full descrip- 

 tion of its peculiar structure, and especially of the great central capsule, which resembles 

 that of the other PH^ODARIA. He first stated that the singular pileated pieces described 

 by Ehrenberg were not complete shells, but isolated pieces of the skeleton, which are 

 scattered in the jelly-envelope around the central capsule in a mode similar to the spicula 

 of Thalassoplancta, Thalassosphcera and Sphcerozoum. Hertwig also first recognised 

 that the thin rods, which compose the reticular pileated pieces of the skeleton in 

 Dictyocha, are not solid bars, but thin hollow tubules, similar to the hollow rods of 

 Aulacantha and of other PH^EODARIA. 



Numerous complete and well-preserved specimens of Dictyocha, which I found in the 

 collection of the Challenger, have convinced me that the accurate description of 

 R. Hertwig is correct in every respect, and that these remarkable bodies are true 

 PUJEODARIA, most closely allied to Cannobelos ( = Thalassoplancta) and to Aulacantha 

 (compare PI. 101, fig. 10). I now regard them as representatives of a peculiar 

 subfamily of Cannorrhaphida, which I call Dictyochida. To the same subfamily also 

 belong the small annular bodies which Ehrenberg described in 1841 as Mesocena 

 (loc. cit., p. 401), and the elegant, more complicated, reticular and pileated bodies, 

 which Stohr figured in 1880 under the name Distephanus (Palasontogr., vol. xxvi. 

 p. 121). These peculiar bodies are also only isolated pieces of the siliceous skeleton, and 

 are scattered tangentially in great numbers in the calymma, around the tripylean central 

 capsule. A still higher degree of development is attained by the interesting forms 



