REPORT ON THE RADIOLARIA. 



1573 



the nucleus is filled up by protoplasm, containing numerous spherical vacuoles of equal 

 size (v) ; each vacuole encloses a small, dark, fat-granule. The large nucleus (n) is 

 either spherical or lenticular, and more or less depressed in the main axis ; its diameter is 

 usually about half as great as that of the enclosing capsule, 0'05 to 0*15, rarely less or 

 more ; it contains, enclosed in a clear mass, numerous dark, roundish or oblongish 

 nucleoli (Z). 



Numerous preparations of Aulacanthida exhibited a central capsule with two 

 nuclei (PL 101, fig. 6), or a calymma with two central capsules (PL 104, figs. 1, 3) ; 

 so that the process of propagation by self-division, observed already in many different 

 PH^EODARIA, seems to happen very frequently in the Aulacanthida. The voluminous 

 phseodium is usually about twice or three times as large as the central capsule, and 

 covers its oral or anterior half; the colour of the roundish phaeodella composing it is 

 sometimes more green or brown, at other times more blackish. The roundish alveoles, 

 which fill up the rather firm jelly of the calymma, exhibit nearly the same shape as in 

 the common Thallassicolla nucleata. The surface of the calymma is usually pro- 

 tected by the dense veil of tangential needles, and often forms conical or tent-shaped 

 elevations around the bases of the piercing radial tubes (PL 102, fig. l). 



Synopsis of the Genera of Aulacanthida. 



{Surface of the calymma naked, without tan- 

 gential needles, . 

 ,.,,. 

 Surface of the calymma covered by a veil of 

 tangential needles, .... 



Radial tubes without lateral branches, j Terminal branches simple, 

 but with a verticil of terminal < 

 branches. ( Terminal branches forked or again ramified, 



Radial tubes with lateral and with 

 terminal branches. 



Lateral branches verticillate, . 



Lateral branches irregularly scattered, not 

 verticillate, .... 



665. Aulactinium. 



666. Aulacantha. 



667. Aulographis. 



668. Auloceros. 



669. Aulospathis. 



670. Aulodendron. 



Subfamily 1. AULACTINIDA, Haeckel. 



Definition. A ulacanthida without external veil of tangential needles on the 

 surface of the calymma. 



Genus 665. Aulactinium, 1 n. gen. 



Definition. A ulacanthida without a veil of tangential needles, with simple 

 radial tubes, which bear neither lateral nor terminal branches. 



1 Aulactinium = ~W iih radial tubes ; %;, &XT/;. 



