189&] MICROSCOPICAL JOURNAL. 235 



it appears to occupy an intermediate position between 

 the group so provided and that which is quite destitute. 

 Widely distributed, but rare outside the British area. 

 Fig. 7 x 300. The figure exaggerates the diameter of the 

 filaments. 



Achlya fluxuosa. — This organism possesses nearly all 

 the features of A. gracilis, but instead of having the 

 rigid appearance of the latter, the superficial branches 

 are beautifully curved , the individual plants are smaller 

 and nearly circular in contour ; it appears to quickly erode 

 the surface of the shell, leaving continuous channels 

 which present a serrated appearance at the margins. 

 The cavities which terminate the shorter branches are 

 irregular in form ; some are nearly globular, others 

 cylindrical, and occasionally they assume the form of lit- 

 tle groups of filaments built up like a. string of beads, 

 like the reproductive bodies of Penicillhim glaucum ; but 

 whatever their form, they occasionally appear to be 

 thickly beset with short hair-like appendages. Compar- 

 atively common in littoral deposits of the Cornish and 

 Devonshire coasts. Fig. 8 x 180. 



Achlya articulata. — A very well defined species, but 

 rather difficult to detect owing to the plants being rather 

 small and usually rather deeply immersed in the sub- 

 stance of the shell they invade. The filaments are com- 

 posed of numerous elongated pear or club-shaped joints, 

 articulated in a regular system, the bulbous parts being 

 the growing ends. The joints more deeply situate ap- 

 pear to be destitute of appendages, but as they approach 

 the surface rather long simple tubular processes are de- 

 veloped. The plants branch rather freely and in moder- 

 ately thick shells ; several whorls may be observed, 

 causing the organism to assume the form of a bush in 

 miniature. Very rare. Found at Challenger stations 127 

 and 187, and in littoral material from Whitesand Bay, 

 Cornwall. Fig. 9 x 300. 



