NO. 1 TAYLOR: PACIFIC MARINE ALGAE 297 



Digenia simplex (Wulfen) C. Agardh 



Taylor 1928, p. 175, pi. 24, fig. 20, pi. 33, fig. 7. 



Both the DeToni and Engler-Prantl descriptions of this genus indicate 

 that the maximum number of pericentral cells in the lateral branchlets is 

 8, but examination of the I. Soccoro material showed most commonlj' 9 or 

 10. The main axes show a well-defined relatively small-celled cortex with 

 thicker walls, and a large-celled medulla with thin cell walls, but no rec- 

 ognizable axial or pericentral cells in the mature portions. 



Mexico: Is. Revilla Gigedo, forming large tufts in the tide pools 

 along the shore of Braithwaite Bay, I. Soccoro, no. 39-51, 18 Mar. 1939. 

 Costa Rica : common in tide pools near the entrance on the western side 

 of the bay, Golfo Dulce, no. 39-95, 26 Mar. 1939. 



BRONGNIARTELLA Bory, 1822 

 Brongniartella mucronata (Harvey) Schmitz 



Plants erect, bushy, when well developed to 2-3 dm tall, with several 

 axes from the expanded holdfast, alternately several times branched, the 

 branches and indeterminate branchlets with 5 pericentral cells, early corti- 

 cated ; becoming naked below but above bearing determinate monosipho- 

 nous branchlets which fork dichotomously but commonly with one side 

 of the fork not rebranching, tapering to the tips with the terminal cell 

 small, very acute and slightly indurated ; tetrasporangia single in the seg- 

 ments of lesser branches near the tips, somewhat spirally disposed. 



Hoyt 1920, p. 506; Taylor 1928, p. 167, pi. 27, figs. 5, 6. 



This species is represented by one fragment 5 cm tall, agreeing in all 

 essentials with the somewhat variable West Indian plant. One notes that 

 the lateral determinate branchlets are, on small and particularly slender 

 branches, simple or subsimple and only in somewhat older or more sturdy 

 parts become several times branched. They are, in our Mexican material, 

 about 30 II in diameter at the base and 18 /a in the lesser divisions. The 

 tetrasporangia are 60-70 /x diam. There is little of generic value to dis- 

 tinguish Veleroa (Dawson 1943, p. 335) from Brongniartella except the 

 number of pericentral cells, reported to be 4 instead of the 5 characteristic 

 of well-developed shoots of Brongniartella. 



Mexico : Nayarit, rare as dredged from 22 meters' depth at sta. 970 

 near I. Maria Magdalena, Las Tres Marias, no. 39-660 (tetrasporic), 9 

 May 1939. 



