REPORT ON THE RADIOLARIA. 1021 



those quadrupedal forms in which two opposite sagittal feet (the caudal and sternal) 

 alternate in the form of a cross with two jjaired lateral or pectoral feet (Tetraspyrida, 

 PL 53, figs. 19, 20). In many Spyroidea the number of basal feet is greatly 

 increased, and they form a regular radial corona around the basal plate, like a circle 

 of tentacles (Polyspyrida, PI. 87). In this latter case the feet are usually flat and 

 lamellar, whilst in the other groups they exhibit a very variable form, as is seen in 

 Pis. 83 89. 



The Central Capsule of the Spyroidea has been accurately observed in only a few 

 genera, and requires a further exact examination regarding the different modifications 

 which occur in their different famihes. It is very probable that these will agree with the 

 well known modifications in the corresponding groups ofCyrtoidea. The characteristic 

 Monopylean structure of the capsule (with porochora and podoconus) was first described 

 by Eichard Hertwig in his Ceratospyris acuminata (loc. cit., p. 72, taf. vii. fig. 2). I 

 found the same afterwards in many other forms. In the Zygospyrida and Tholospyrida 

 the central capsule seems to be usually bilobate (bisected by the sagittal ring), and 

 enclosed in the two chambers of the cephalis. The two lobes of the capsule (right and 

 left) are equal and connected by a smaller middle part, which contains the transverse 

 elliptical nucleus and is enclosed by the sagittal ring ; often each lobe contains a large 

 oil-globule. In some forms, however, three or four lobes (sometimes perhaps more) are 

 developed, which pierce the cortinar pores of the basal plate and depend freely between 

 the basal feet (PL 53, fig. 19). In the Phormospyrida and Androspyrida the formation 

 of such basal lobes seems to be more frequent ; they are here enclosed by the thorax. 

 Usually each lobe contains a large oil-globule. In Nephrospyris (PL 90) and in some 

 similar genera the central capsule is vioUn-shaped, deeply bisected by the sagittal ring ; 

 in each of the two lobes a series of oil-vesicles is developed at both poles of the transverse 

 axis (figs. 7, 10) ; the nucleus, a transverse cylindrical body, is placed in the latter. In 

 the periphery of the voluminous calymma of this singular genus a large number of 

 globular cells are developed (figs. 7, 10), probably symbiotic xanthellae. In some forms 

 of Nephrospyris these xanthelte are enclosed by a pecuHar inflated girdle, developed in 

 the periphery of the kidney-shaped skeleton (PL 90, figs. 1, 4-6). 



Synopsis of the Families of Spyroidea. 



Shell without thorax ; no second shell- | Cephalis without galea (or apical cupola), 1. Zygospyrdja. 

 joint, developed from the base of the ■' 

 cephalis. ( Cephalis with a galea (or apical cupola), . 2. Tholospyrida. 



Shell with a thorax, or a second shell- ( Cephalis without galea (or apical cupola), 3. Phoemospyrida. 

 joint, developed from the base of the -' 

 cephalis. | CephaHs with a galea (or apical cupola), . 4. Andeospykua. 



