REPORT ON THE RADIOLARIA. 47 



spicula now straight, now curved, commonly of very different size. (Often one single quadriradiate 

 spiculum is distinguished by its extraordinary size.) For the detailed description of this species 

 compare my Monograph (loc. cit.). 



Dimensions. Diameter of the central capsules 0'05 to 0'35, length of the simple needles 

 O'Oo to 0'25, shanks of the quadriradiate spicula 0'05 to 015. 



Habitat. Mediterranean, Messina, Naples, Nice. 



4. Rhaphidozoum arachnoides, u. sp. 



Spicula of two different kinds ; one kind simple, needle-like, the other quadriradiate ; both 

 very thin and slender, smooth, without spicules. Simple needles curved, C-shaped. Four shanks 

 of the quadriradiate spicula also curved, commonly of nearly equal size. The numerous thread-like 

 spicula of this species are so densely packed around the central capsule, that they extend all around 

 its surface like the network round a balloon. 



Dimensions. Diameter of the central capsules 012 to 015, length of the simple needles 01 

 to 012, shanks of the quadriradiate spicula 0'06 to 0'08. 



Hulitat. Tropical Atlantic, Station 345, surface. 



5. Rhaphidozoum asperum, n. sp. 



Spicula of two different kinds ; one kind simple, needle-shaped, stout, and straight, the other 

 kind hexaradiate; its six shanks about half as long as the former, conical. Both kinds very thorny, 

 covered with short conical spinules. 



Dimensions. Diameter of the capsules 0'06 to 0'08, length of the simple needles O'Oo to 0'07, 

 shanks of the hexaradiate spicula 0'03 to 0'04. 



Habitat. South Pacific, Station 288, surface. 



Subgenus 2. Rhaphidoceras, Haeckel. 



Definition. Spicula of two different kinds ; one kind simple, needle -shaped, the 

 other kind geminate-radiate, with rays on both poles of a middle rod. 



6. Rhaphidozoum neapolitanum, Haeckel. 



Sphcerozoum neapolitanum, C. Brandt, 1881, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, 

 p. 390, Taf. i. figs. U, 16-18. 



Spicula mixed, of two different kinds ; simple needles and geminate-forked. Simple rods, 

 like those of Bdonozoum italicum, more or less curved, pointed at both ends, smooth (sometimes a 

 little thorny at both ends). Geminate spicula simply forked, like those of Sphccrozaum furcatum, 

 composed of a short, simple, axial rod, and two simple, smooth, straight shanks on each end of it, 

 commonly somewhat longer than the middle rod. This species, which I have observed myself in 

 Spezzia in great quantity, is quite as variable as all the other species of the genus, and has not more 

 claim to specific rights than the others. Commonly the simple needles are much more numerous 



