85 



and by thin places in the longitudinal walls, after the manner of the cells of M,etagoniolithon\ 

 but the thin places are smaller than in this latter genus. In yania and Corallina it appeared 

 to me that the cells adhered only at their primary pores and that secundary ones were scarce 

 or very obsolete, for the cells seemed always to be quite free from one another in transverse 

 direction. The nodes in all four genera consist of one row of long pericline cells, surpassing 

 many times (even so much as 1 1 times) the length of the cells of the central strand. I Saw 

 no layer of "Deckzellen" at the top of the branches. 



The conceptacula grow on the cylindrical or winglike broadened joints in Arthrocardia 

 and at the top of the joint, immersed in its tissue in Cheilosporn/n, but I have seen many 

 specimens to which the words of Gray could be applied, that it was difficult to say to which 

 group they belonged. Many algae considered till now to belong to the genus Amphiroa must 

 be placed in the genus Arthrocardia : 



Amphiroa tnbcrculosa (P. & R.) Setch. & Gardn. 



Amphiroa cretacea (P. & R.) Aresch. 



Amphiroa variabilis Harv. 



Amphiroa Darwiui Harv. 



Amphiroa rudis Harv. 

 . Amphiroa cpiphiegnoidcs Ag. 



Amphiroa vertebralis (Harv.) Aresch. 



Amphiroa declinata Yendo. 



Amphiroa aberrans Yendo. 

 and perhaps others, that I have not seen. Amphiroa TJ'ardii Harv. and A. Stangeri Harv. 

 were already taken out of the genus Amphiroa by Areschoug. 



Corallina and Jania are easily known from the preceding genera because they bear 

 their conceptacula immersed at the top of the branches. In Corallina the cells of the central 

 strand are relatively short for such sturcly plants and have the same size throughout the joint. 

 In Corallina officinalis, C mcditerranea and C. Cuvieri the cells of the nodes are many times 

 longer than the cells of the central strand in the joint. 



In Jania adhaerens and J. rubens the cells of the central strand in the joint are relatively 

 long for such slender plants and the cells in the node are not longer, sometimes shorter, as a 

 rule of the same size. This is beautifully illustrated by Kützing Phycologia generalis pi. 79, 

 fig. I and II. Fig. I shows a node of C officinalis and part of the two neighbouring joints, 

 and we see that the cells of the node are much longer than the cells of the joint; in fig. II 

 we see a short-celled node of Jania rubens and the long cells of the joints still partially covered 

 by cells of the cortical layer. 



In Jania longifurca the cells of the node are twice as long as those of the central 

 strand in the joint. Jania longifurca is a transition from the Corallinae with long-celled nodes 

 to such Janiae as have short-celled nodes. 



This difference in length of cells of the node, being as far as I know, the only difference 

 between Jania and Corallina, is not a very striking character; still it may be a help in disen- 

 tangling the confusing group of Corallinae, and the name of Jania ma)- perhaps be retained 



