GRAF ZU SOLMS-LAUBACH— MOJvOGRAPH OF THE ACETABULAlUEJi. 37 



EXPLANATION OP THE PLATES. 



Plate I. 



Fig. 1 . Acetabularia crenulata, Lamour, The fertile shoot with several caps cut in half vertically ; on 

 the corona of the highest the branched hairs still remain. Between each two caps there is a 

 whorl of scars which had borne a sterile crown of hairs. Slightly magnified. 



2. Ditto. Apical view of the corona superior, with two liair-scars, one behind the other, on each 



portion, x . 



3. Ditto. Longitudinal section of a ray of the cap, showing the vestibule and the prominences of the 



coronae superior and inferior, the former provided with hair outgrowths : a, the central portion 

 of the disc : b, the sporangium, x . 



4. Acetabularia mediterranea, Lamour. Longitudinal section of a cap during development. At a 



the globular^ raised apex of the shoot ; at v the vestibule, of which the partition-wall towards 

 the ray has been formed ; at b the portion of the corona superior with developing hairs, below 

 which, and without doubt laterally, the sporangium c begins to shoot out. X . 



5. Ditto. Longit. section through a ray of an almost mature cap, showing vestibule, coronae 



superior and inferior : a, the central portion of the disc ; b, the sporangium. X . 



6. Acetabularia Kilneri, Agardh. Side view of two cap-rays, showing the peculiar thickenings 



characteristic of the species, x . 



7. Acetabularia mediterranea, Lamour. Longit. section of young cap during development of sporan- 



gium. This {a) has already pressed the apex and the portion of the corona superior into a lateral 

 position ; b, the corona superior ; c, the central portion of the disc, x . 



8. Ditto. Longit. section of a very young cap which scarcely shows the differentiation of corona 



and sporangium. X . 



9. Acetabularia Suhrii, Solms. Corona superior from above. x , 



10. Acetabularia caraibica, Kiitz. End of sporangial ray filled with spores, x . 



11. Acetabularia dentata, SoIttis. Ends of two cap-rays. X. 



12. Acetabularia mediterranea, Lamour. External view of the cap during development, (From the 



same specimen as fig. 8.) X • 



13. Acetabularia Suhrii, Solms. Disc seen from below : at a, the vestibule; at b, the corona inferior; 



at c, the sporangia. 



Plate IL 



Fig. 1. Acetabularia exigua, Solms. Side view of a complete decalcified specimen. X. 



2. Acetabularia Peniculus, R. Br. Longit. section of a specimen with two caps, one above the other ; 



of which the lower one is anomalous in producing on its branches secondary caps of more or 

 less completeness ; a represents their sporangia, x . 



3. Acetabularia parvula, Solms. View of the corona superior from above, x . 



4. Acetabularia exigua, Solms. View of the cap from above. Only the bases are drawn of tlie 



sporangia and of the hairs in the coronal prominences, x . 



5. Acetabularia parvula, Solras. Cap seen from above, showing the abundant calcification of the 



partitions between the rays. X • 



