1888-89.] Mr John Rattray on the Genus Goscinodiscus. 653 
( Lateral areolse larger, non -protuberant ; intervals 
I expanding slightly outwards. No areolate central 
j area, ......... concinna. 
j Lateral areolse not larger ; intervals of uniform 
j breadth ; a central areolate area, .... decora. 
, ~ j Lateral areolse not larger, but larger areolse at inner 
* } ends of compartments, gradually decreasing away 
j from the rays; a central rosette; compartments 
( with inner ends convex; intervals of equal breadth, cximia. 
| Lateral areolse not larger. Compartments with inner 
| ends mostly convex. No areolate central area. 
L Intervals expanding somewhat outwards, . . marylandica. 
( Lateral areolse protuberant, 
16.-! Lateral areolse non-protuberant; intervals expanding 
^ slightly outwards. No central areolate area, 
17. 
crenata. 
f Intervals narrow, frequently almost occluded at the 
j inner ends. A central areolate area, . . . vulgaris. 
17. ■{ Intervals narrow, sometimes expanding outwards ; 
j contiguous to the large areolse, a narrow' hyaline 
L band, concave towards border, .... simulans. 
f Intervals between compartments obsolete, a large 
j subcuneate areola at sides of each compartment, 
j and contiguous to that of adjacent compartments, rylandsiana . 
I Intervals present. No such subcuneate areolse, . 18. 
( Markings on compartments subgranular, few towards 
18.-! their inner ends, ....... punctata. 
V. Markings on compartments areolate throughout, . 19. 
,q f No central areolate area, 20. 
* \ A central areolate area present, .... 21. 
f A subasteromphaloid centro-lateral area differentiated 
1 inner ends of compartments transversely truncate 
* ] intervals attenuating outwards, 
l No such subasteromphaloid area, 
dallasiana. 
22 . 
(Rays sharply bigeniculate beyond their middle; 
| compartments with inner ends slightly swollen, 
22. -{ faint lines passing inwards a short distance from 
j their inner ends, ....... bribissoniana. 
LRays straight, 23. 
23. 
' A circular hyaline central space ; compartments with 
inner ends convex centrally, the intervals of 
uniform, breadth, reaching f- of radius from centre, 
Compartments with inner ends transversely truncate 
to slightly concave inwards ; intervals short, ex- 
tending to half length of compartments, 
- Compartments with inner ends somewhat obliquely 
I truncate ; intervals of equal breadth, outer ends 
close to border. Rays sometimes dichotomous, 
Compartments with inner ends transversely truncate, 
to concave ; rays straight or curved, frequently 
branching 2 to 4 times before reaching half distance 
_ to compartments, 
balearica. 
Icevis. 
rotula. 
princeps. 
fTwo rays passing to apex of one of the compart- 
21.-! ments, an apiculus at outer end of each interval, . uraster. 
No such radii, 24. 
