PALMELLACE.E. 9 



GENUS 4. UROCOCCUS. Hass. (1845.) 



Cells large, globose, or oblong, reddish or blood-red ; tegu- 

 ment thick, gelatinous, concentrically larnellose ; stem thick, 

 gelatinous, often ringed or annulate. 



All the species in this genus are rare, and with one exception confined 

 to Britain. We are, therefore, compelled to reproduce figures already 

 published, without measurements or information beyond the original 

 descriptions. 



The peculiar structure of the pedicellate cells is thus described by 

 Braun : " The large globular brownish-red or blood-red cells throw off 

 colourless layers of cell membrane, which appear to be separated by 

 intermediate layers of softer jelly, whence arises a distinctly concentric 

 structure of the envelope. But the enveloping layers of Urococcus do 

 not retain their original form and integrity ; not increasing themselves 

 in size, they are pushed off on the upper side by constantly succeeding 

 inner coats, being at first merely attenuated at one side, but subse- 

 quently, as it seemed to me, actually broken through. Since this emer- 

 gence from the old coats is always repeated on the same side, a mem- 

 branous-gelatinous peduncle is produced formed of cups fitted one into 

 another, so as to give an annularly streaked, apparently shortly articu- 

 lated aspect. The red cell, which occupies the summit of this peduncle, 

 sometimes divides, and this of course produces a subsequent dichotomy 

 of the peduncle. If the periods of the formation of the separate 

 enveloping layers were known, the age of the little plant, whose 

 history is preserved in the gelatinous peduncle, might be determined by 

 the number of rings." Rejuvenescence, p. 179. 



* Stem annulate. 

 Uxococcus Hookerianus. Hass. Alg.t. 80, f. 4. 



Cells globose, or elliptic, variable in size, blood-red, granular, 

 stem more or less elongated, often divided, densely ringed. 



SIZE. Cells -013--06 mm. (Rabh.}. 



Rabh. Alg. iii. 31. 



Hoematococcus Hookeriaua^ Berk. & Hass. in Hass. Alg. p. 

 325, t. 80, f. 4. 



On chalk cliff, &c. 



Plate IV. fi(j. 1. a, cells considerably magnified, after Hassall ; b, 

 cells further magnified, after liabenhorst. 



Urococcus insignia. Hass. Alg.t. 80, /. 6, a. b. 



Cells large, globose, blood-red ; stem abbreviated, remotely 

 annul ated. 



Rabh. Alg. iii. p. 31. 



Hcematococcus msignis, Hass. Alg. p. 324. 



" This very fine species I have never met with in any considerable 

 quantity. Scattered isolated globules I have frequently met with, and 

 these occasionally attached to a closely corrugated or ringed mucous 

 appendage. Each globule is usually surrounded by a single vesicle or 

 ring ; in some globules, however, there are as many as four or five en- 

 closing vesicles." Hassall. 



Plate IV. fit). 2. a, b, cells considerably magnified, after Hassall. 



c 



