REPORT ON THE RADIOLARIA. 1751 



dense fork-thicket. Whilst in Ccelotholus each frontal main tube (arising from the 

 frontal corner of the galea at right and left) is divided into an anterior or pectoral, and 

 a posterior or tergal style, in Ccelothamnus each of these two divergent main styles is 

 again forked, so that the total number of projecting and radially diverging styles amounts 

 to sixteen. One Mediterranean species of this genus. Ccelothamnus davidqffii, has been 

 already described by Biitschli in 1882 (Zeitschr. f. wiss. Zool., vol. xxxvi. p. 486, 

 Taf. xxxi.). Though its description on the whole is accurate, some important errors, 

 which may be here corrected, are to be met with. The two central valves of the lattice- 

 shell (dorsal and ventral) are symmetrically equal in size and in form, as in all other 

 Coelographida ; the different forms and the inverse arrangement of the two valves, 

 described by Biitschli (pp. 488, 491), were effected by an artificial dislocation and 

 inversion. The peculiar opening a, which, according to his opinion, was supposed to 

 bring about a direct communication between the cavities of the galea and its valve, is in 

 reality the optical section of the rhinocanna, the two convergent frenula of which (y) he 

 figured, but did not recognise. Ccelothamnus attains the greatest size among all 

 Radiolaria ; the diameter of the body in Ccelothamnus maximus amounts to 33 mm. 



1. Ccelothamnus bivalvis, n. sp. (PI. 122, figs. 69). 



Sixteen styles all of equal length, about three times as long (in their free part) as the diameter 

 of the dense fork -thicket. The size of the anchor-pencils tapers from the proximal to the distal 

 end. Each of the four primary frontal tubes (which arise in opposite pairs from the frontal corners 

 of the two gale;e) is twice forked, and so produces four styles. 



Dimensions. Diameter of the whole body 18, of the fork -thicket 2 - 4 to 3'0. 



Habitat. North Atlantic, Canary Islands, Station 354, surface. 



2. Ccelothamnus davidoffii, Biitschli. 



Cailothamnus davidoffii, Biitschli, 1882, Zeitschr. f. wiss, Zool., vol. xxxvi. p. 486, Taf. xxxi. 



Sixteen styles all of equal length (?), about four times as long (in their free part) as the 

 diameter of the fork-thicket. The size of the anchor-pencils is nearly equal throughout their 

 entire length. (Compare the careful description of this species by Biitschli,) 



Dimensions. Diameter of the whole body 15, of the fork-thicket l - 8. 



Habitat. Mediterranean (Villafranea, near Nice), Davidoff,. surface, 



3. Ccelothamnus sedecimalis, n. sp. 



Sixteen styles straight, of different sizes. The pectoral or anterior branch of each frontal main 

 tube is simple, and twice as long as the diameter of the large fork-thicket. The tergal or posterior 

 branch is forked at the base, and its anterior branch is again forked in the middle part, so that three 



