534 Proceedings of Royal Society of Edinburgh. [sess. 
Yar. arafurensis. Gran., Denh. Wien. Ah., 1884, p. 79. 
C. papuanus , Cstr., Diat. Chall. Exped., p. 154, pi. iii. fig. 3. — 
Diam. *152 to '475 mm. Central space minute, surrounded by a 
minute and inconspicuous rosette, sometimes hardly differentiated. 
Markings 9 to 12 in '01 mm. 
This form is frequent in the Arafura Sea. The central space is 
smaller than figured by Castracane in all the specimens I have 
observed, and is not of specific value, as he maintains. He has over- 
looked the distinct marginal processes characteristic of the species. 
Habitat. — Arafura Sea, H.M.S. Challenger (Rae ! Castracane) ; 
between Kerguelen and Heard Island, H.M.S. Challenger (Rae !). 
C. africanus , Janisch. Sch., Atl., pi. lix. figs. 24, 25. — Sub- 
circular or roundly elliptical. Diam. -035 to '088 mm. Central 
space and rosette absent. Markings polygonal, increasing gradually 
outwards, and again smaller at the border ; towards the centre 6, 
towards the border 4 in '01 mm.; irregular on an indistinctly 
defined somewhat excentric area, elsewhere the rows radial, straight, 
or slightly bent, sometimes indistinctly subfasciculate towards the 
border. Border regularly striated, sometimes double ; the inner 
portion about J of the breadth of the outer. Sometimes also with 
more evident striae ; oblique curved, more distant and more distinct 
lines. — Janisch, Gazelle Exped. y taf. iii. fig. 2. 
This species is readily distinguished by the character of its 
border. From C. vetustissimus, Pant., it differs by the absence of 
a nodule from the excentric area. 
Habitat. — Gazelle Expedition (Janisch); Newcastle, Barbados 
(Firth) ; off Ascension Island, S.S. Buccaneer (Grove !). 
Yar. wallichiana, Grun. Cleve and Moll., Diat., No. 183, 207. 
— Diam. '05 to '0575 mm. Central space irregular, excentric, with 
a few isolated rounded granules. Markings rounded, granular ; 
towards the excentric area 8, about the semiradius 5 to 5J, at the 
border 6 in *01 mm.; rows radial, straight; at irregular intervals 
hyaline, narrow radial spaces passing inwards for a short distance 
from border. Border distinct; striae delicate, 10 to 12 in '01 mm. 
— C. africanus, var. rotunda , Cstr., Diat. Chall. Exped., 1886, p. 
159, pi. xxiv. fig. 3. — (PL II. fig. 4.) 
