( 192 ) 



very dark in the mass. Favellse terminal on shortened branches, " fre- 

 quently suiTounded by dichotomous ramuli," mostly bilobed, rather 

 large. TetrasjDores elliptical, sessile, opposite the axils of the uj^per 

 ramuli, generally abundant. 



This species is remarkable among its congeners by the denseness of 

 its branching, in the mass more resembling a bit of sponge than any 

 thing else. In this respect it more nearly resembles G. arhusada than 

 any other species of the genus, but is even more densely ramified than 

 that species, and retains the water in the manner of a sponge. 



From C. arhuscula it is not always easily distinguished at first sight, 

 but in the microscope it may be readily known by its differently formed 

 articulations, eveiy one of which emits its ramulus ; each ramulus thus 

 consists of a single articulation, whereas in C. arhuscula the ultimate 

 ramuli are multiarticulate. In the ]- resent species the tetraspores are 

 solitary, and in C arhuscula they are arranged in continuous rows along 

 the uj)per edge of the ultimate ramuli. 



On the east coast, C. arhuscula is one of our most common species, 

 while C. granulatum is only occasionally observed ; the former mostly 

 on mussel-shells, the latter more frequently parasitical on other Algse, 

 and not usually in fruit. 



EXPLANATION OF TLATE CXXIX. 



Fig. 1. — CalUthamnion granulatum, natural size. 

 2. — Ramulus with tetraspores. 

 3. — Tetraspore. 

 4. — Ramulus witli favella3. 

 5. — Joint of the stem. All macinified. 



