Vol. 51.] RADIOLARIAST ROCKS IN THE LOWER CULM MEASURES. 641 



Genus Amphibrachtum, Haeckel. 



Test consisting of a central chamber and two opposite chambered 

 arms. 



Amphibrachium, sp. a. PL XXVII. fig. 7. The test is -25 mm. 

 in length, the central chamber -09 mm. in diameter ; the arms are 

 equal and of the same width throughout, their ends are rounded or 

 truncate. Only the outlines of the form are shown. Not uncommon. 

 Carzantic Quarry, near Launceston. 



Amphibrachium, sp. b. PI. XXVII. fig. 5. As seen in section 

 the central chamber is oval, and the arms fusiform or elliptical in 

 outline, with obtuse ends. Total length *39 mm., length of central 

 chamber -1 mm., greatest width of the arms '05 mm. Carzantic 

 Quarry. 



Genus Phopalastrum, Haeckel. 



The test consists of three chambered arms. 



Rhopalastrum ingens, sp. nov. PI. XXVII. fig. 6. As shown in 

 section, the three arms are unequal ; the longest is fusiform in out- 

 line, thickest in the middle portion, and gradually tapering to an 

 obtuse end; its length is -63 mm., and greatest width -11 mm. 

 The other two arms are even throughout; the longest measures 

 ■56 by "08 mm., and the other, which appears to be incomplete, 

 is *45 by -095 mm. No structure has been preserved, but its form 

 and proportions readily distinguish it from other species which have 

 been described. Pare. Pamshorn Down. 



Rhopalastrum clavatum, sp. nov. PI. XXVII. fig. 9. The test 

 is not inflated in the centre, and gives no indication of a central 

 chamber; the arms are club-shaped and subequal. Length of each 

 arm -47 mm., greatest width -1 mm. Traces of pores are shown. 

 Pamshorn Down. 



Rhopalastrum, sp. a. PL XXVII. fig. 8. Only two of the three 

 arms remain in this specimen. The arms are club-shaped and 

 rounded at the ends and subequal. Length *53 mm., breadth "17 mm. 

 in the thickest parts. There is no central inflation. In general form 

 this specimen resembles R. Isselii, Piist, from the Lower Carboni- 

 ferous of Sicily, but is much larger. Pamshorn Down. 



Subclass NASSELLAPIA, Haeckel. 

 Order CYRTOIDEA, Haeckel. 

 Genus Sethocapsa, Haeckel. 



The latticed test is divided by a constriction into two chambers, 

 and the aperture is covered by a latticed plate. 



Sethocapsa, sp. a. PL XXVII. fig. 17. The lower chamber is 

 nearly circular in outline, and *13 mm. in diameter, the upper is 

 represented by a subcylindrical extension, "16 mm. in length by 



