254 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 12 



KEY TO SPECIES 

 1. Plants very tiny, less than 1 cm tall, with a few very thin-walled 



small vesicles B. tenuissima 



1. Plants several centimeters tall, with large vesicles 



B. pseudodichotoma 



Botryocladia tenuissima n. sp.^^'^ 



Plants minute, solitary or to three on a base, vesiculate on a short 

 stipe, the stipe 35-140 fi long, the oval sac 1.0-2.25 mm diam., structurally 

 showing an inner cortical layer of thin-walled polygonal cells 30-60 ^ 

 diam., smaller and rounder near the apex, larger and a little elongate 

 toward the base, the outer cortex very slight, consisting of cells 4.5-12.0 fi 

 diam., with chromatophores, arranged along the lines of contact of the 

 inner cortical cells in a single row, or occasionally in as many as three 

 irregular rows, of which one is larger and somewhat under the other two, 

 in no case covering more than a minor part of the underlying cell ; spo- 

 rangia tetrapartite, immersed at the angles between the inner and the 

 outer cortical cells, round-oval, to about 20-24 /x, long; internally pro- 

 jecting glandular cells problematical, but if present single, small, and 

 scattered. 



These tiny, fragile specimens seem quite mature, since richly tetra- 

 sporangial. Notable is the exposure of the inner cortex cells to the surface, 

 and the general absence of outer cortex cells except along the contact mar- 

 gins of the underlying cells. No clearly recognizable gland cells were 

 seen. This seems to be the smallest species of the genus yet recorded, while 

 the specimens of B. pyriformis secured off Aruba I. (Taylor 1942, p. 117) 

 with sacs to 5 cm long, carried the largest vesicles. 



Ecuador: Archipielago de Colon, very rare as dredged from 55 

 meters off Post Office Bay, I. Santa Maria, no. 34-382 A (tetrasporic, 

 TyP£),29 June 1934. 



Botryocladia pseudodichotoma (Farlow) Kylin 



Plants to 5 cm tall (and elsev/here reported to 2 dm), from a small 

 irregular holdfast, the axes and branches cartilaginous, slender and terete, 

 dividing alternately, terminating in oval vesicles 1-3 cm long, 7-13 mm 



157 Botryocladia tenuissima n. sp. — Plantae soHtariae aut fere solitariae, ves- 

 iculatae in stipite brevi, vesicula 1.0-2.25 mm diam., praedita atque, solis in mar- 

 ginibus cellularum corticis interni conterminarum, strato corticeo imperfecto cellu- 

 larum 4.5-12.0 n diam., in 1-3 ordinibus; tetrasporangiis ad angulos inter cellulas 

 medullares, rotundato-ovatis, 20-24 n long. Planta typica in loco dicto I. Santa 

 Maria, Ecuador, legit W. R. Taylor no. 34-382A, 29 June 1934. 



