20 



L. HILLIS-COLINVAUX 



under incrassata (Section IV). The species incrassata (tridens) and 

 monile were new with Elhs, whereas opuntia had been described by 

 Linnaeus in his "Systema Naturae" (1758), using the binomial Corallina 

 opuntia. Others before this had assigned other names to it, generally 

 polynomials. 



Ellis' examination of Halimeda material included microscopical 

 study of both surface and internal features (Fig. 12) in what seems to 



,^ 





20. The Corallina incradata, from the Weft- 25. 



Indies. 



21. One of the joints of its natural fize. 26. 



22. The fame magnified a little, to (hew its 



pores in its calcareous furface. 



23. Part of the infide tubes of the joint, of 27. 



their natural fize. 



24. The fame magnified, to £hcw the openings 



of the cells on the furface, con- 

 nedled together. 



A perpendicular feftion of half of one of 

 thefe joints. 



The fame magnified, to fhew the figure 

 of the vefTels leading to the fuckers 

 in the calcareous furface. 



A piece of the calcareous furface highly 

 magnified, to ihew fome of the pores 

 open, and others covered with their 

 convex opercula ; letter a fhews the 

 figure of one of the trumpet-fhaped 

 fuckers highly magnified. 



Fig. 12. Halimeda (Corallina) incrassata. These illustrations with analysis, by Ellis 

 (1767), provide the type description of the species incrassata. Ellis' work also 

 represents the earliest known microscopical study of the genus. The habit (No. 20) 

 illustrates the caulescent effect obtained when basal segments remain unbranched. 

 In older plants a number of basal segments may become consolidated into a relatively 

 massive structure. (From Ellis (1767); photograph composition by The Ohio 

 State University Department of Photography.) 



