( 146 ) 



abbreviated branches. Tetraspores terminal on the apices of the ultimate 

 ramuli. 



This beautiful species, one of the prettiest of a very handsome genus, 

 is by no means of unfrequent occurrence in this country, and Dr. Harvey 

 informs us {Phyc. Brit.) that it is frequent in the Mediterranean, and 

 that he has received specimens from Tasmania, Cape Horn, and Noi-th 

 America, showing that in the temperate latitudes of both the northern 

 and southern hemispheres it is widely distributed. To the naked eye 

 the species presents nothing very distinct or remarkable, but seen 

 through the microscope the peculiar ramification is very apparent, is 

 most beautiful, and can never be mistaken for any other. The naked 

 eye, however, fails to detect anything in the external habit of the 

 plant which will readily form a primd facie character, and we have 

 no doubt that this delicate little gem is in consequence often over- 

 looked, and may yet be found in many j)laces where its presence has 

 not yet been detected. 



Although no plant is more constant to its characters, yet these often 

 present considerable latitude in their development, according to the 

 luxuriance of the siDecimen. In small specimens the plumules are often 

 only once pectinated, whilst in those of more luxuriant growth they are 

 occasionally thrice, or even some of the lower ones partially and rarely 

 four times pectinated, and Dr. Harvey mentions a variety in which they 

 were twice the usual length but much more slender. 



We scarcely know a more beautiful object for the microscope than a 

 fragment of the present species, especially when in fruit ; the beautiful 

 regidarity of the closely pectinated I'amuli, the deep tint of the internal 

 bag of endochrome, enclosed in its pellucid cylinder, dotted over with 

 deep red fruit, render it exceedingly beautiful. 



EXPLANATION OF PLATE CXVIIL 



Fig. 1. — Callithamnion plumula, natural size. 

 2. — Plumule with favelte. 

 3. — Same, more magnified. 

 4. — Pinnule with tetraspores. 

 5. — TetrasiDores from same. All magnified. 



