the under side of the upper joint as may 1»' seen distinctly in fig. i i on PI. XVI. The upper side 

 of the node is covered by overlapping layers of calcified tissue. The cortical Iayer has a very 

 great development in the joint; the conceptacula appear on both sides of the joint hut they are 

 only slightly prominent and often entirely immersed by subsequent growth of the frond. 



S. Amphiroa crassa Lamx. PI. XV. fig. i — ;. 



Amphiroa crassa Lamouroux. Voyage de 1'Uranie par Freycinet. Zoölogie par Quoy et 



Gaimard 1S24. 

 Amphiroa Godeffroyi Grunow. Algen der Fidschi, Tonga und Samoa Insein. In Mus. Godef- 



froyensis at Hamb. sub nom. A. robusta. 



Stat. 282. East Point of Timor. 

 Stat. 303. Haingsisi, Island Samau. 

 Stat. 304. Lamakera, Island Solor. 

 Southcoast of Java. leg. Teysman. 



Fronds articulated, branching di-trichotomously or irregularly, many joints springing from 

 one broad joint. Adventitious branches arise from the joint never from the node. Central strand 

 built up of one, two or more rows of long cells, foliowed by a row of shorter cells, very short 

 ones were not observed. Length of long cells from 80 — 100 ij., of short ones from 32 — 36 u.. 

 Cortical layer much developed. Node consisting only of the central strand, many rows of cells taking 

 part in its formation. Calcified cortical layer surrounds the node entirely or splits horizontally 

 leaving the node naked for a very short space. When the cortical layer does not split, a little 

 constrictton of the frond is the sole indication of the node. Conceptacles superficial, often overgrown 

 by cortical layers and sunk deep into the frond. Diameter of conceptacles 320 — 340 ij.. 



I got this beautiful Amphiroa first at the East Point of Timor. It is closely allied to 

 A. tribulus Lamx, both having the same way of forming their nodes; but whether they belong 

 to one species I could not ascertain •, the material of A. tribulus that I had at my disposal 

 was scanty and presented quite a different aspect. 



. /. crassa however is a variable plant; I have specimens 8 cm. high, erect, branching 

 dichotomously and spreading widely, with long, relatively thin joints and other specimens 

 from 2 — 6 cm. high with short, broad joints. Again other specimens connect both the former 

 specimens in an unmistakeable marmer. The specimens with the long joints were described by 

 GrüNOW as A. Godeffroyi. 



I believe that a small alga, that I got on a former voyage in the Archipelago at 

 Sikka. Island of Mores, is a dwarf form of A. crassa. It has the same way of formine its 

 node and is in all respects like the type but it is not higher than 1 — 1,5 cm. It may be 

 distinguished as f. minuta. 



When I began my study on the Amphiroae of the Siboga Expedition, I did not intend 



write a monograph of the genus. For the sake however of those who would like to name 



phiroac. with reference to the structure of the node, I have made the following key. 



species of which I have only seen one or two specimens and for the specihc 



value of which I would not be held responsible, I have marked with a f. 



