294 PERCY SLADEN TRUST EXPEDITION 
3. Dasyopsis GEppit, n. sp. (Plate 17. figs. 18-20; Plate 18. fig. 33.) 
Thallo carnoso, plano, palmato, inciso, horizontaliter expanso, sympodialiter con- 
structo, ad apicem radioso ; divergentia ignota. Penicillis lateralibus tantum bene 
evolutis, dorsalibus et ventralibus aliquamdiu conspicuis, postea evanescentibus. 
Ramis lateralibus pro parte cum axi principali coalitis. Strato corticali cellularum 
rotundarum aut angulosarum contiguarum. Antheridiis cylindricis in turmis in 
facie inferiori thalli sitis. Cystocarpiis et stichidiis ignotis. 
Amirante, 20-25 fms.; in alcohol. 
Cargados Carajos, 25 fms. 
Chagos Archipelago, Salomon Atoll, reef; in alcohol. 
Coetivy, reef. 
Dasyopsis Geppit has a broad, flat, fleshy frond, slightly palmatifid and attached to 
the substratum by a thick pedicel (Pl. 17. figs. 18, 19). Its outward appearance 
differs entirely from any known species of Dasyopsis, and it is only by the study of 
the youngest segments of the frond that an insight into its anatomical structure is 
obtained. This is in principle like that of Dasyopsis, but differs in so far as the 
displaced branches, instead of turning in every direction, as they do in D. Stanleyi, 
spread themselves principally in a bilateral direction and grow congenitally into a 
leaf-like frond. The penicilli are situated on the margin of this frond, but also on its 
upper and lower surface; the cells of the filaments have a breadth of 16-28 , and 
a length of 32-88, 100, and 140 pz. 
At the top of the different segments the penicilli are so closely packed together, in 
consequence of the smallness of the cells, that it is impossible to trace the central 
tube down into the frond or to observe the divergence of the penicilli around its apex 
(Pl. 18. fig. 33). 
Dorsi-ventral organization does exist, though I could not trace it at the apex of the 
frond. The ventral side, that turned towards the substratum, bears antheridia at 
the base of old penicilli. The antheridia stand in groups of five and six together 
(Pl. 17. figs. 19, 20), and are borne on a monosiphonous pedicel. The dorsal side of the 
frond is barren in all my specimens. The position of the antheridia is interesting, 
for D. Geppii is both a reef and a deep-water plant. If it were only collected on the 
reef, one might infer that the antheridia kept to the ventral side to ensure ‘protection 
from the sun, but since these alge have been found with ventrally placed antheridia, 
not only on the reef but also in deep water, this explanation does not hold good. 
Dorsi-ventral organization of any kind was hitherto unknown in Dasyopsis, 
I have great pleasure in dedicating this alga to my kind friend, Mr. Gepp, of the 
British Museum. 
4. DASYOPSIS PALMATIFIDA, n. sp. (Plate 17. fig. 21.) 
Thallo carnoso, plano, profunde palmatifido, segmentis aut laciniis seepe terminan- 
tibus in filamento cylindrico, substrato bulbo affixo. Segmentis ad apicem radiatis, 
postea horizontaliter expansis. Penicillis circum apicem thalli bene eyolutis, 
infimis evanescentibus. Penicillis constantibus e filis multo crassioribus quam 
