TRIBE I. ASTR.EACEA. 341 



8. A. MYCEDIA FRAGILIS. (Dana.} 



A. unifrons, stipitata, late explanata, et subhypocrateriformis, tenuis- 

 sima; polypis parvulis, scepius transverse seriatis, seriebus per cottes 

 elongatas 1 J'" latas separatis. Corallum margine subpapyraceo, longe 

 pellucido etfragili; fossis vix f" profundis, et ad marginem caliculis 

 seriatis instructis, cettis (oririmis) $'" latis ; subtus subtilissime stri- 

 atum et concentrice undulatum. 



Unifacial, stipitate, broadly explanate, and somewhat hypocrateriform, 

 very thin ; polyps small, mostly in series, which are separated by 

 even ridges 1J lines broad. Corallum with the margin subpapyra- 

 ceous, and, for a considerable breadth, translucent and quite fragile; 

 fossae scarcely | of a line deep, and often near the margin composed 

 of seriate calicles ; cells (oririmes) f of a line broad ; under surface 

 very finely striate and concentrically undulate. 



West Indies. Boston Nat. Hist. Soc. 



This species has much the habit and appearance of an Undaria, 

 and in size and thickness is near the spedosa ; but the oririmes are 

 like small cells, and the fossa3 consist mostly of a series of them. 

 Near the margin, there are distinct calicles, many isolated, others in 

 lines, but each with its own convex exterior. The specimen examined 

 was six inches by four and a half in breadth, with the concavity an 

 inch deep; the corallum was about an eighth of an inch thick at 

 centre, and hardly an eighth of this at the margin, which, for an 

 inch, was translucent. In the centre of the frond, the ridges become 

 nearly obsolete. This species has much of the habit of the A. undata, 

 and might, with equal propriety, be placed among the Undariae. 



II. Glomeratce, sed basi explanatce. 



9. A. MYCEDIA GIBBOSA. (Dana.) 



A. crasse gibboso-glomerata, et angulata, subtus late planulata, parce 

 undulata et centra stipitata ; polypis scape reticulate subseriatis, scepius 

 spar sis ; cottibus undique reticulatis, triangulatis, etfere acutis, fossis 



86 



