130 MRS. A. WEBEE-VAK BOSSE ON THE 



?. Dasyoi^sis Geppii, n. sp. (Plate 13. figs. 18-2.0 ; Plate 14. fig. 33.) 

 Thallo carnoso, piano, palmato, inciso, horizontaliter expanse, sympodialiter con- 

 structo, ad apicem radioso ; divergentia ignota. Penicillis lateralibiis tantum bene 

 evolntis, dorsalibus et ventralibus aliquamdiu conspicuis, postea evanescentibus. 

 Kamis lateralibus pro parte cum axi prineipali coalitis. Strato cortical! cellularum 

 rotundarum aut angulosarum contiguarum. Antlieridiis cylindricis in turmis in 

 facie inferior! thalli sitis. Oystocarpiis et sticliidiis ignotis. 

 Amirante, 20-25 fms. ; in alcohol. 



Cargados Carajos, 25 fms. 



Cliagos Archipelago, Solomon Island, no indication of depth ; in alcohol. 



Coctivv, reef. 



Dasyopsis Geppii has a broad, flat, fleshy frond, slightly palmatifid and attached to 



the substratum by a thick pedicel (PL 13. figs. 18, 19). Its outward appearance 



differs entirely from any known species of Lasyopsis, 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 JDasyopsis, but differs in so far as the 

 displaced branches, instead of turning in every direction, as they do in B. Stanleyi, 

 spread themselves principally in a bilateral direction and grow congenitally into a 

 leaf-like frond. The penicill! 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 /x. 



At the top of the differ 



penicill! are so closely packed together 



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 penicill! around its apex 



(PL 14. 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 penicill!. The antheridia stand in groups of five and six together 

 (PL 13. 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 iihe ventral side to ensure protection 

 from Ihe sun, but since these algse 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 13. fig. 21.) 



Thalio carnoso, piano, profunde palmatifldo, segmentis aut laciniis ssepe terminan- 

 tibus in filamento cylindrico, substrato bulbo afiixo. Segmentis ad apicem radiatis, 

 postea horizontaliter expansis. Penicillis circum apicem thalli bene evolutis, 

 infimis evanescentibus. Penicillis constantibus e filis multo crassioribus quam 



