268 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 3 



Foslie and Howe (1906) have illustrated Goniolithon strictum van 

 nana, which is in many ways strikingly like the present species. Should 

 the large conceptacles prove to be tetrasporangial, this plant would 

 probably fall into Goniolithon. In this case it will be difficult to establish 

 points of distinction between the Gulf plants, G. frutescens and G. 

 strictum. The last two species are admittedly indistinct (Foslie & Howe, 

 1906, p. 131). 



Lithophyllum Hancockii sp. nov. 

 Plate 55, Fig. 1 ; Plate 62, Fig. 1 



Frondes crusta tenui affixae, ramos dense et irregulariter conglobatos emit- 

 tentes, usque ad 7 cm. altae ; ramis superne 1.5 mm. diam., verrucosis forma irreg- 

 ularibusque, inferne multo coalescentibus, superne liberis; conceptaculis tetra- 

 sporangiiferis profunde immersis, 240 \.i diam., 110 |li altis, poro apicali aperienti- 

 bus, columna centrali paraphysium e basi assurgenti et tetrasporangiis circumdata. 



Plants attached to corals and stones by a thin crust, shrubby, forming 

 densely and irregularly branched clusters to 7 cm. high and 10 cm. across; 

 branches about 1.5 mm. diam. in upper parts, warty and irregular in 

 form, much coalesced or anastomosed, but free in upper parts, with 

 rounded or truncate apices, in longitudinal section showing a large hypo- 

 thallic region and a sometimes feebly, sometimes well-developed peri- 

 thallic layer, up to 250 ii thick; hypothallus cells in upper parts 8-11 /a 

 broad by 18-23 fi long, symmetrically arranged in very regular concentric 

 rows; perithallus cells usually short, square or slightly flattened to 1.5 

 times as long as broad, usually distinctly smaller in all dimensions than 

 hypothallus cells and somewhat less regularly arranged ; tetrasporic con- 

 ceptacles deeply immersed, 240 fx diam., 110 ;u, high, opening with a 

 single apical pore, with a central column of paraphyses, rising from the 

 conceptacle floor and surrounded by tetrasporangia, these 50-60 /i, by 

 25-30 II. 



Type: D. 619a, shallow water of San Gabriel Bay, Espiritu Santo 

 Island, February 14, 1940. Herb. AHF no. 22. 



This plant shows considerable resemblance to Lithophyllum trichot- 

 omum but may be distinguished on several points. The clusters are larger 

 than are common in the latter species, the branching more irregular and 

 warty, more compact and anastomosed throughout. Whereas in L. trichot- 

 omum the outgrowths of the basal crust are straight, erect, symmetrical 

 structures, those of L. Hancockii arise as irregular lobed branches. The 

 conceptacles are much smaller than any observed in L. trichotomum. It 

 differs from L. frutescens in the size of the tetrasporic conceptacles and 

 tetrasporangia. 



