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



Legion I. SPUMELLARIA, 

 vel Peripylea, vel Peripylaria (Pis. 1-SO). 



Spumellaria (exclusis Spyridinis), Ehrenberg, 1875. 



Peripylea (inclusis Thalassicollis et Sphserozois), Hertwig, 1879. 



Peripylaria (inclusis Collodariis et Polycyttariis), Haeckel, 1881. 



Definition. Radiolaria with simple membrane of the central capsule, which is every- 

 where perforated by innumerable very fine pores. Extracapsulum without phseodium. 

 Skeleton wanting or siliceous. Fundamental form originally spherical. 



The legion SPUMELLARIA vel PERIPYLEA, in the extent here defined, was constituted 

 by me in 1883 in my paper on Die Ordnungen der Radiolarien. 1 I propose to retain 

 for this legion either the name SPUMELLARIA of Ehrenberg (1875) or PERIPYLEA of Hertwig 

 (1879), although both groups have not quite the same extension. "We exclude from the 

 SPUMELLARIA the Spyridina (united with them by Ehrenberg) and include the Collodaria. 

 With the Peripylea of Hertwig we unite his Thalassicollea and Sphserozoea. To avoid 

 any confusion it would perhaps be better to name this legion " Peripylaria." 



The SPUMELLARIA agree with the ACANTHARIA in the structure of the simple capsule- 

 membrane, which is perforated by numerous small pores (but devoid of the large main 

 opening, which the NASSELLARIA and PH^ODARIA possess), whence we unite both the 

 former as Holotrypasta, both the latter as Merotrypasta. 



The difference between the two legions of Holotrypasta is determined by the 

 skeleton, which in the SPUMELLARIA is either siliceous or wanting, whilst in the Acantharia 

 it consists of the peculiar organic substance, acanthin. 



The legion SPUMELLARIA is by far the largest and most important of the four legions 

 of Radiolaria, as well with respect to the number of different forms, as to the enormous 

 masses of individuals, which we encounter living and fossil. We distinguish in this 

 legion not less than thirty-two different families, three hundred and sixteen genera, and 

 more than seventeen hundred species. 



The classification of this large group requires for its better comprehension a careful 

 division into larger and smaller groups. We divide it therefore first of all into two orders, 

 Collodaria and Sphserellaria, as proposed in the paper mentioned above. 2 



The Collodaria have no perfect latticed skeleton, and comprise two suborders 

 or sections : in the Colloidea the skeleton is entirely wanting, in the Beloidea 

 it is represented by a variable number of siliceous needles or spicules, scattered in the 

 calymma around the central capsule. 



1 Sit;.umjsb. med.-nat. Gesellsch. Jena, February 16, 1883. 2 Loc. cit. 



