80 MR. J. B. CARRCTHERS ON THE CYSTOCARPS OF 



cells of the medullary layer are larger in this specimen ; but a 

 more essential difference exists in the fact that the cystocarps 

 are not in the middle of the thallus, but the swelling projects 

 considerably on one side and very slightly on the other. In 

 a transverse section the nucleus can be clearly seen occupying a 

 position nearer the swollen than the comparatively flat side of 



the cystocarp. 



The composition of the fruit and the anatomical structure of 



the thallus do not point to the position of this alga in the 

 genus Rhodymenia, Grrev., but rather in the Section V. of Callo- 

 phyllis, J. Agardh (' Epicrisis Floridearum ') ; but I had not a 

 sufficient amount of material to thoroughly compare this specimen 

 with the described species of that Section. 



. The study of the above-mentioned specimens of Rhodymeniaper- 

 tusa, J. Agardh, and R. peruviana, J. Agardh, from the herbarium 

 of the British Museum, leads to a similar result. Both specimens 

 are from the collection of Dickie, and are dated from the North- 

 west coast of America ; but both plants prove, on examination, to 

 be incorrectly determined. In both cases they appear to belong 

 to the genus CallopJiyUis ; but I was not able, owing to lack of 

 material for comparison, to determine accurately their specific 

 position. 



The attempt to learn the structure of the cystocarps of Rhody- 

 inenia pahnata, Grrev., from the two specimens in the Natural 

 History Herbarium has not been successful; and as these cysto- 

 carps have not yet been discovered — though the other methods of 

 propagation of this species, viz. antheridia and tetraspores, have 

 frequently been found — it is not possible to conjecture as to the 

 character of these fruits of this species ; and it is possible that 

 the discovery of the structure of the cystocarp may lead to the 

 classifying of Rhodymenia palmata in a different position. 



I have also not been able to examine the cystocarps oiR. peru- 

 viana \ but I have studied the fructification of the third species 

 of this section, viz. R. pertusa, J. Agardh. I had the fortune to 

 see one of the specimens which Harvey has mentioned. The 

 plant, now in the herbarium of Trinity College, Dublin, was col- 

 lected by Lyallin 1858 on the north-west coast of America (Point 

 Roberts). On this specimen the cystocarps occur all over the 

 surface of the segments, which are much perforated ; the majority 

 are very young, and project very little from the surface of the 

 thallus. 



