Johnson. — Sphaerococcus coronopifolius, Stackh. 301 
the family. Its thallus is readily conformable with that of 
Sphaerococcus , though its procarpia and fruit- development are 
not yet known. Kiitzing 1 describing .S', coronopifolius as 
mentioned under the name Rhynchococcus , places Rhyncho- 
coccus with Calliblcpharis in the family Rhynchococceae. If the 
latest view, that of Schmitz, be followed and the genus 
Nitophyllum be regarded as one of the Sphaerococcaceae, this 
family presents a striking example of the difficulty of deter- 
mination of the exact systematic position of a genus from 
a consideration of the structure of its thallus ; for in these 
three genera we have examples of three of the four main 
types of thallus-structure met with in the Florideae 
1. In the simplest Florideae (many of the Helmintho- 
cladieae) there is a uniseriate cellular central axis with apical 
growth and bearing numerous free lateral radiating branches. 
This type is not represented in the Sphaerococcaceae. 
2. The lateral branches (also uniseriate, cellular, branching, 
and apically growing) have become more or less closely 
applied to one another so as to form a loose cortex to the 
distinct central axis. This- type, seen in the Gelideae and 
Rhodomeleae (e.g. species of Polysiphonia :), is represented by 
Sphaerococcus. 
3. The lateral branches are closely applied to, and as well- 
developed as, the central axis, which is no longer distinguish- 
able as such (Corallineae). Represented by Gracilaria. 
4. The lateral branches are closely applied to one another, 
and occur right and left of the parent axis in one plane, 
essentially giving the thallus a flattened parenchymatous 
character (some of the Rhodymenieae). Represented by 
Nitophyllum. 
Supposing the accounts of the structure of the procarpia 
and of the development of the cystocarp in Sphaerococcus and 
Gracilaria to be correct, I still refrain from any attempt to 
assign to them any other position than that they at present 
occupy, hoping that when more genera have been examined 
1 Kiitzing, Phyc. Gen., p. 403 (1843). 
