142 Universitu of California Publications. [Botany 



It is because of this fact that the two marine species just 

 discovered ou the Pacific Coast of North America (an Ulva- 

 composite collected on the Bay of San Francisco, and a 

 Prasiola-composite collected on the coast of Alaska), are 

 especially noteworthy. 



THE ULVA-COMPOSTTE. 



The Ulva-composite is a deep green when young but a dark 

 olive to almost l)lack when old. When dried it becomes a dull 

 dark olive, the older i^lants always being the darker. The 

 stipe and basal portions of the frond are always of a lighter 

 color, and often almost a translucent greenish tan. 



The fronds vary greatly in shape, from narrow lanceolate to 

 oblanceolate or even sometimes to oval, but the broad lanceolate 

 is typical. The frond narrows gradually into a short slender 

 stipe growing from a disk-like hold fast. Occasionally a speci- 

 men is found in which all the fronds arise from the tip of a 

 single slender stipe. The old fronds are very seldom regular in 

 outline, as the tips and edges have been torn, broken, or con- 

 tracted and distorted in various ways. Occasionally specimens 

 are collected wdiich send out small fronds and bud-like projec- 

 tions from the edges and surfaces of the main frond, giving it a 

 very shaggy or ragged appearance. 



There is a very great variation in the size as well as in the 

 shape of different fronds as they measure from 1 to 2.5 cm. in 

 length and 1 to .">() mm. in width. The average plant is about 

 1.5 cm. high. The typical plant has one frond always much 

 larger than the others; and all diminishing until the smallest is 

 scarcely visible. (Cf. Fig. 1, PI. 15.) 



The surfaces are much roughened by the perithecia, which are 

 dark l)rown or l>lack wart-like eruptions scattered irregularly 

 over the frond from near the base to the tip. The perithecia vary 

 in shape and size, but are usually hemispherical with a concave 

 lighter colored apex, and are scattered over both surfaces of the 

 frond. The surfaces of the frond are also usually corrugated or 

 wrinkled and warped, as if stretched in some parts and con- 

 tracted unequally in otln-rs. Often one or both edges of the 



