56 West & West. — Observations on the Conjugatae. 
a parallelism of modification has gone on in the reproduction 
of Spirogyra and certain filamentous Desmids, as shown by 
the obsolete Rhynchonema and the laterally conjugated Spoil- 
dylosium. 
We cannot but regard the Mesocarpeae and the Pyxisporeae 
as the most highly specialized families of the Conjugatae, the 
formation of the sporocarp being a faint indication of an 
‘ alternation of generations V 
There is a little retrogression in the Mesocarpeae, certain 
plants of this family (placed under a distinct genus— Goiiato- 
nenia) producing spores only asexually. The accompanying 
phylogenetic table has been drawn up to graphically illustrate 
the conclusions we have arrived at. 
DESCRIPTION OF PLATES IV AND V. 
Illustrating Messrs. West’s paper on Conjugatae. 
PLATE IV. 
Figs. 1-9. Gonatonema Boodlei, West and G. S. West. From Mitcham Common, 
Surrey, x 520. 
Figs. 10-1 5. Gonatonema tropicum , West and G. S. West. From Huilla, Angola, 
W. Africa, x 520. 
Fig. 16. Mougeotia sp. Showing organ of attachment, x 120. 
Figs. 17-19. Mougeotia sp. Showing short lateral branches, x 120. From 
Frizinghall, W. Yorks. 
Figs. 20, 21. Spirogyra sp. With rhizoids ; from Hanka Deela, Somaliland. 
X 120. 
Figs. 22-33. Hyalotheca neglect a, Racib. x 520. From the New Forest, 
Hants. 22, vegetative filament with wide gelatinous sheath; 23-27, showing 
formation of aplanospores ; 28-29, zygospores; 30-33, single cells with irregu- 
larity of pyrenoids. 
Figs. 34-36. Cosmarium sphagnicolum, West and G. S. West, x 520. From 
Mossdale Moor, Widdale Fell, N. Yorks. 34, with normal pyrenoids ; 35 and 36, 
with irregular pyrenoids. 
1 The Mesocarpeae afford a better example amongst the lower Algae of 
a sporophyte-generation and a rudimentary alternation of generations than that 
shown by the Oedogoniaceae. 
