OF THE COSCINODISCEiE. 



820 



2 * Disc tcith a central hyaline umhiUcuSy 

 which often resembles a perforation. 

 {The species are commonly smaller than 

 those of the preceding section.^ 



C. actinochilus (E,). — Granules in close 

 lines, radiating- from tlie distinct punc- 

 tated umbilicus, separated from the mar- 

 gin by a border of puucta arranged in 

 close, short, radiating lines. EM. 

 pi. .35 A. 21. f. 5. Antarctic Sea. The 

 radiatino- series of granules are close, 

 but distinct. 



C. ZuncB (E.). — Granules equal, ar- 

 ranged in distinct series, radiating from 

 the smooth umbilicus, and separated from 

 the margin by a border of minute pimcta. 

 EM. pi. 35 a. 21. f. 7. Antarctic Sea. 

 Somewhat resembles C. actinochilus, but 

 has fewer rays, the marginal puncta are 

 more obscure, and the umbilicus is 

 smooth. 



C. gemmifer (K.). — Disk with con- 

 spicuous granules, arranged in lax and 

 elegantly radiating lines from a smooth 

 umbilicus; border minutely punctated. 

 EM. pi. 35 A. 22. f. 3. Antarctic Sea. 

 Bermuda deposit. The rays are fewer 

 and more distant than in the two pre- 

 ceding species ; but all agree in having 

 well-marked grantdes, distinct rays, and 

 minute submarginal pimcta. Diam. 

 1-456". Very like Pyxidicula gemmifera, 

 but larger and more depressed. 



C. apiculatus (E.). — Cellules rather 

 prominent, apiculate, rendering the sur- 

 face rough, subequal, radiating, 10 in 

 1-1200";' umbilicus smooth. EM. pi. 18. 

 f. 43. America. Diam. 1-324". Has 

 a general resemblance to Pyxidicula 

 gemmifera. 



C ])erforatus (E.). — Cellules minute, 

 arranged in close, radiating series ; um- 

 bilicus smooth, resembling a perforation ; 

 margin finely rayed. EM. pi. 18. f. 46. 

 America. Diam."^ 1-348". Difiers fr*om 

 C. fimhriatus by its umbilicus. 



C. disciger (E.). — Differs fr'om C. per- 

 foratus by its irregularly circular, not 

 smooth, and larger umbilicus, and by its 

 rery minute and dense punctiform cel- 

 lides. KSA. p. 123. Virginia. Diam. 

 1-480". Cellules about 30' in 1-1200". 



C. ApolUnis (E.). — Disc with nume- 

 rous series of very dense, equal, puncti- 

 form granules, radiating from a small 

 umbilicus. EM. pi. 35 a. 22. f. 4. Ant- 

 arctic Sea. It difiers from C, Lunce by 

 the gTeater number and denseness of its 

 rays, which, however, although nume- 

 rous, are distinct. Diam, 1-432". 17 

 granules in 1-1200". 



Q. cingulatus (E.). — Disc with very 

 dense, pmictiform granules, indistinctly 

 radiating from a small clear umbilicus ; 

 margin with an annular band capable of 

 being detached. EM. pi. 35 a. 21. f. 6. 

 Fossil. America, Antarctic Sea. 26 gra- 

 nides in 1-1200". Diam. 1-552". Resem- 

 bles C. Apollinis, but its granules are 

 denser and less distinctly radiating. 



3* No ttmhilical vacancy; disc tcith a 

 striated border distinct from the rim. 



C. Jimbriatus (E.). — Cellules small, 

 subequal, obsoletely radiating, near the 

 margin smaller and arranged in radi- 

 ating lines resembling strice. E. /. c. 

 pi. 22. £ 2. Fossil. Sicily. 



C. 7narginatus(E.). — Cellules in curved 

 lines ; marginal ones smaller and ar- 

 ranged in radiating lines resembling 

 striae. E. /. c. pi. 18. f. 44. Recent and 

 fossil. America, Cuxhaven. Cellules 9 

 or 10 in 1-1200". 



C. limbatus (E.). — Central cellides 

 largest, not radiating, outer ones small- 

 est, crowded, arranged in radiating lines 

 resembling stride. E. /. c. pi. 20. 1. f. 29. 

 Fossil, Greece. Diam. 1-576", The 

 largest 7 in 1-1200". 



C. striatus (K.). — CeUides irregularly 

 crowded in the middle ; margin of disc 

 with radiating strict. KB. t. 1. f. 8. 

 Cuxhaven. Diam. 1-456". 



4 * Disc with radiating series of cellides ; 

 no distinct umbilicus, nor striated border 

 distinct from the rim. 



C. gigas (E.). — Disc very large ; cel- 

 lules large, hexagonal, radiating, largest 

 at the margin, decreasing towards the 

 centre. EM. pi. 18. f. 34. Virginia ; 

 Maryland ; alive, Cuxhaven. The largest 

 species of the genus, and well character- 

 ized by its large hexagonal cellules gra- 

 dually decreasing in size from the margin 

 to the centre. Rim striated. 



C. excavatus (Grev. MS.). — Disk large, 

 with hexagonal cellules decreasing in 

 size towards the centre, which has three 

 conspicuous depressions alternating VNdth 

 the same number of elevations. Pisca- 

 taway deposit. The disc in this species 

 is, from its large size, visible to the 

 naked eye, and, like C. gigas, it appears 

 ring-like, the smaller central cells being 

 then invisible. There is no distinct um- 

 bilicus ; but the central portion, including 

 the elevations and depressions, is thinner 

 and is rarely foimd perfect. The cellules 

 of the depressions appear smaller and 

 more radiant than the others, (yth. 26.) 



