128 



WEBEE-VAN BOSSE ON THE 



Dastopsis, Zanardini. 



1. Dasyopsis Stanleti, n. sp. (Plate 13. fig. 16.) 



Thallo elongato, subdichotomo, pauce ramoso, penicillis longis, gracilibus cincto; 

 ramificatione radiata, constante e peuicillis basim versus deciduis, spinas non 



qiientibus. Stichidiis oblongis et cystocarpiis ex penicillis orientibus. An 

 tberidiis non visis. Thallo alto 16 cm. Habitu Dasyoi elegatitis, 

 Cargados Carajos, 30 fms. ; in alcobol and dry specimens. 



To rightly understand the new species of Dasyopsis, it may be worth while to give 

 a short account of the characters of the genus. Dasyopsis has a sympodial mode of 

 growth; the stem or axis being composed of short branches with definite growth; 

 these are pushed aside by their own first branch, and the distance between the base of 

 the mother-branch and the point of insertion of its first branch varies in different 



species. 



But this is a feature Dasyopsis has in common with all Dasye^ ; its special character 



consists in the absence of true pericentral cells. The cells that surround the central 

 tube are not originally segments of this tube, as in the other Hhodomelaceae, but they 

 are downward-growing hyphee, the mother-cell of which is cut off from the branch that 

 is pushed aside when sympodial growth sets in (PI. 14. fig. 32, m). The hyphae may be 

 of the same diameter as the central cells, in which case they resemble true pericentral 

 cells, but they have quite a different origin. The displaced branches continue to 

 develop, they are shorter or longer, naked or corticated, according to the species, and 

 carry several monosiphonous filaments, the so-called penicillus, at the apex. 



Dasyopsis Stanleyi consists of a subdichotomously divided principal axis or stem, 

 carrying at indefinite intervals branches of unlimited growth, which may ramify again 

 and are surrounded at the top by monosiphonous penicilli. This pretty alga so much 

 resembles Dasya elegans that I felt at first inclined to take it for that species ; after 

 careful examination, however, I discovered that the plant has the characteristic 



structure of Dasyopsis) the branches of definite growth are separated by only one 

 short segment from each other, and grow out in any direction from the main axis. As 

 every branch or so-called penicillus gives off a downward-growing hypha, the central 

 axis soon increases in thickness ; true pericentral cells are of course absent. 



The penicilli are composed of cells having a breadth of 6-13 yu ; their length varies 

 from being almost square at the base to 72 /x at the top. They are very delicate and 

 soon fall off, unless they happen to bear cystocarps or stichidia at their base. The 

 stichidia were very rare in my preparations ; I observed only one but unfortunately 



r 



lost it ; I saw, however, that it was long and cuspidate. The cystocarps were numer 

 in fertile specimens. 



2. Dasyopsis aperta, n. sp. (Plate 13. fig, 17 ; Plate 14. fig. 32.) 



Thallo ex axibus principal ibus primo surgentibus, postea decumbentibus constante, unde 

 denuo rami adscendentes nascuntur, Apice axis principalis et ramorum penicillis 

 ramulosis, monosiphoniis cincto, penicillorum pilis postea decidentibus, basi 



