1888 - 89 .] Mr John Rattray on the Genus Coscinodiscus. 569 
C. biradiatus. Grey., Trans. Micr. S oc. Lond ., 1861, p. 42, pi. iv. 
fig. 7. — Sometimes elliptical. Diam. *075 to *085 mm. Surface 
slightly convex. Central space rounded, with isolated granules, 
sometimes absent. Markings smallest, rounded, and irregular at 
the centre ; elsewhere obtusely angular, subpearly, enlarging to 
about § of radius to 4 in -01 mm., and again decreasing slightly 
outwards ; rows regular, alternately longer and shorter ; the spaces at 
the origin of the shorter rows smooth, hyaline. A narrow hyaline 
band just within the border. Border with a single band of minute 
granules, 4 in *01. — Sch., Atl., pi. lviii. fig. 2, 
Habitat. — Barbados deposit (Greville ! Cleve) ; Springfield 
deposit, Barbados (Schmidt, Doeg !) ;* Chalky Mt., Barbados 
(Firtli !) ; Oamaru deposit (Grove !) \ Piscataway deposit (Greville!) j 
Sta Monica deposit (Grove !). 
C. elegantulus. Grev., Trans. Micr. Soc. Lond ., 1861, p. 42, 
pi. iv. fig. 8. — Diam. *0425 to *1 mm. Surface slightly convex. 
Central space absent. Markings polygonal, and in contact or 
rounded, free, and without order on a small slightly excentric 
area extending to about J- of radius or onwards to the semiradius, 
thence obtusely quadrangular, 4 to 4J- in *01 mm., subequal, or 
increasing slightly outwards ; rows straight or curved, the shorter 
rows around the border inconspicuous, irregular. Border with a 
single row of minute granules, 8 in *01 mm. — Sch., Atl., pi. lviii. 
figs. 3-5. 
Distinguished from C. biradiatus, Grev., by its more delicate 
markings and its larger central portion upon which these are 
irregularly placed. Its markings are smaller and less pearly than 
those of C. pateUceformis , Grev., to which it is also allied. 
Habitat. — Barbados deposit (Greville ! Firth !) ; Cambridge 
deposit, Barbados (Rae !) ; Newcastle deposit (Firth !) ; Chalky 
Mount, Barbados (Weissflog !); Springfield deposit, Barbados (Doeg! 
Cole !). 
C. aethes, sp. n. — Diam. *05 mm. Surface almost flat. Central 
space quadrate, about tV of diam. broad. Markings round or 
obtusely angular, from the central space to about of the radius 
* In the collection of Dr F. W. Griffin, 
