108 THE LITHOTHAMNIA OF THE PERCY SLADEN TRUST EXPEDITION, 
EXPLANATION OF THE PLATES. 
All the figures from photographs about 2 natural size. 
PraTE 15. 
Lithophyllum Gardineri, Fosl., f. typica. 
Figs. 1-3. Specimens from Salomon Atoll, Chagos, 
Fig. 4. A rather young specimen attached to a fragment of a decaying root: Coetivy. 
Lithophyllum Gardineri, Fosl., f. obpyramidata, 
Fig. 5. A specimen forming a transition to the typical form: Salomon Atoll, Chagos. 
Figs. 6,8. Specimens with much anastomosing and in part rather delicate branches : Egmont Atoll, 
Chagos. 
Fig. 7. Aspecimen seen from below, with the outer branches partly rather dilated at their ends: Coetivy, 
PLATE 16. 
Lithophyllum Gardineri, Fosl., f. subhemispherica. 
Part of the alga seen from above : Egmont Atoll, Chagos. 
