1888 - 89 .] Mr John Rattray on the Genus Coscinodiscits. 567 
few rounded isolated granules. Markings rounded, granular, most 
prominent near the margin of the central space, faint beyond the 
semiradius ; rows widely separated by hyaline interspaces. Border 
distinct, sharply defined, with delicate markings only opposite the- 
ends of tne radial rows. 
Distinguished from C. rotula by its larger markings ; the central 
space does not become excentric. 
Habitat. — Campeachy Bay (Schmidt). 
G. perminutus , sp. n. Melosira? Sch., Atl., pi. lix. fig. 7. — 
Diam. about ’03 mm. Central space distinct, circular, J to J of 
diam. broad. Markings punctiform, with small interspaces ; rows 
straight, interspaces widest opposite origin of shorter rows ; adjacent 
to border a distinct band of large areolae 5 in *01 mm. ; a few 
scattered prominent round granules forming a circlet a short 
distance within the border, and one present at middle of central 
space. Border sharply defined, from J to -J- of radius broad, 
hyaline. 
Habitat. — Campeachy Bank (Schmidt). 
C. lunce. Ehrb., Mon. Ber. Ah., 1844, p. 201. — Diam. *038 to 
‘057 mm. Central space rounded, about Jq of diam. broad. 
Markings rounded, granular, subequal, 6 to 8 in - 01 mm.; rows 
separated by wide hyaline interspaces, only a few passing from the 
central space, adjacent to. the border crowded on a narrow zone. 
Border narrow, hyaline. — Ehrb., Mihrog., pi. xxxv. a. 21. fig. 7; 
Ralfs in Pritch. Inf., p. 829 ; C. cycloteres, Cstr., Diat. Chall. 
Exped., p. 161, pi. xxii. fig. 8. 
Distinguished from C. actinochilus by the less crowded radial 
rows, and the less distinct narrower marginal zone. 
Habitat. — Pancake ice, Antarctic Ice Barrier, lat. 78° 10' S., long. 
162° W.; also lat. 75° S., long. 170° W.; lat. 78° 10' S., long. 162° W., 
190 fathoms; from snow and ice taken from the sea, lat. 76° S., 
long. 165° W., near Victoria land; ex Salpd, lat. 66° S., long. 
157° W.; Gulf of Erebus and Terror, lat. 63° 40' S., long. 55° W., 
207 fathoms (Hooker); lat, 53° 55' S., long. 108° 35' E., 1950 
fathoms; H.M.S. Challenger (Castracane, Rae !). 
O. trochisehos. Tru. and Witt, Jeremie Diat., p. 14, pi. ii. 
