REPORT ON THE RADIOLARIA. 1743 



silica here completely separates the cavities of the valve and of the rhinocanna resting 

 upon it. 



The "frenula or nasal suspensoria" (PI. 127, figs. 4-9fc) are thin ligaments of silica, 

 which connect the nasal mouth (m) with the base of the main tubes arising from the ^alea: 

 they are, therefore, also common to all Coelographida, and an exclusive and marked 

 attribute of this family. They are, however, difterent in the two suljfamilies of this 

 group, corresponding to the different origin of the odd or paii-ed main tubes. In the 

 Coeloplegmida (Pis. 126-128) from the apex of each galea arises an odd main style, the 

 nasal style {g l), and its base is connected with the nasal mouth by an odd frenulum (6). 

 In the Coelotholida however (PL 122) the large nasal odd style is always wanting, and 

 there arise two paired frontal tubes from the two corners of the truncate frontal face of 

 the galea ; therefore two paired frenula are developed (a right and a left), and these, 

 converging towards the nasal mouth, connect its distal corner with the base of the two 

 frontal tubes. 



The odd frenulum of each valve of the Coeloplegmida lies therefore in the sagittal 

 plane, whilst the two paired frenula of the Coelotholida lie on both sides of it, to the right 

 and left. The frenula seem to be su2iporting columellse or pillars, which support the 

 fragile skeleton, and mainly effect a fixed prop for the fragile galea. In the Coelotholida 

 the frenula are often rather broad and irregularly fenestrated lamellaj of silica (PI. 122, 

 fig. 2), whilst in the Coeloplegmida they are usually thin ligaments, fenestrated only at 

 the broadened ends, which are inserted inside on the distal apex of the nasal mouth, 

 and outside on the base of the nasal main styles. 



The large hollow tubes which arise from the galea of all Coelographida, are very 

 variable in number, size and shape, but are always richly branched and symmetrically 

 arranged in the dorsal and the ventral valve of the shell. They exhibit an important 

 difference in the two subfamilies of the group ; in the Coelotholida aU the branches, and also 

 the thin terminal ramules, are free, without any junction ; in the Coeloplegmida, however, 

 they communicate by frequent anastomoses, and the connected terminal ramules form on 

 the surface of the calymma an outer lattice-mantle of very delicate network. Another 

 marked difference between the two families is indicated by the origin and site of those 

 main tubes which are connected with the rhinocanna by a frenulum. In the Coelo- 

 plegmida an odd, very large main tul^e (the nasal style) arises from the anterior apex of 

 each galea and bears on its base an odd frenulum. This nasal style and its frenulum is 

 altogether wanting in the Coelotholida, where two paired main tubes (the frontal tubes) 

 arise from the lateral corners of the truncate anterior side of the galea, and are connected 

 with the mouth of the rhinocanna by two paired convergent lateral frenula. 



We distinguish in all Coelographida two different forms of hollow branched tubes, 

 which we will call " brushes " and " styles." The brashes are dichotomously branched 

 from the base, not verticillate ; their distal ramules remain separate in the Coelotholida 



