V. CRYPTONEMIACE.E. 197 



after strong South Westerly gales. They are apparently immature, but unques- 

 tionably congenerous with A. prismntims, with which they agree in structure and 

 substance. Possibly mature specimens may be more compound. 



XXI. PPJONITIS. /. Ag. 



Frond compressed or flat, linear, dichotomous or pinnate, proliferous or glandular 

 on the disc or margin, composed of three strata ; the medullary stratum very broad, 

 of densely interwoven, slender filaments; the intermediate of roundish cells, smaller 

 towards the surface ; the cortical of minute, coloured, vertically seriated cellules. 

 Nuclei (faveUce) immersed either in the frond or its marginal processes, simple, con- 

 taining roundish spores within a gelatinous pellicle, at length discharged through a 

 superficial pore. Tetraspores oblong, cruciate, dispersed among the cells of the 

 cortical layer. 



Rather coarse Algte, of a thick, coriaceous or rigid substance and very dense tex- 

 ture, linear, nerveless, pinnate or dichotomous, often much branched, frequently 

 margined with minute glands, which afterwards grow out into lobules. Most turn 

 very dark in drying. 



The species here brought together have been formerly arranged with SpJuvrococcns, 

 Gelidium or Grateloupia ; and are nearly related to the latter genus, difi'ering chiefly 

 in the more compound structure of the frond. Eight species are enumerated by 

 Agardh, all natives of the Pacific Ocean, three being found to the north, and five to 

 the south of the equator. 



1. Prionttis lanceolata, Harv. ; frond piano-compressed, linear, alternately or 

 irregularly branched ; branches ligulate, attenuate at the base and apex, naked or 

 pinnate ; pinnaj lanceolate, distichous, mostly opposite ; tetraspores cruciate, im- 

 mersed in the pinnules. Prionkis ligidata, J. Ag. Sp. Alg. vol. 2^ p. 189. Gelidium 

 lanceolatum, Harv. in Bot. Beechey^ p. 164. (Tab. XXVII. A.) /3 angusta ; much 

 more slender, forked, with few and nearly naked branches. 



Hab. Prince William's Sound and Nootka, Mr. llenzies, 1787- California, Doug- 

 las ! Dr. Coulter ! /3 St. Francisco, Capt. Pike. (v. s. in Herb. T. C. D.) 



Root discoid. Fronds tufted, twelve or fourteen inches long, one to two lines 

 wide, much compressed or nearly flat, linear, tapering to the base and apex, alter- 

 nately branched or pinnate. The primary branches are several inches long, quite 

 snnple, and either naked or distichously pinnulate. Pinnules about half an inch 



