Mr. H. J. Carter on a Freshwater Species of Echinocystidia, 263 



Acanthocystis turfacea, n. sp. et geu.? 



Globular, subround, of a green colour, loricated, spiniferous, 

 and tentaculiferous. Lorica flexible, covered with minute, fusi- 

 form, slightly curved spicules, which give the outline a fibrous 

 wavy appearance. Spines straight, hollow, of uniform breadth 

 in the shaft, bifid or forked at the distal, and discoid at the 

 proximal extremity, which rests upon the lorica ; very numerous, 

 apparently rigid, radiating or turned across each other and move- 

 able as the spines in Echinus. Tentacula three times the length 

 of the spines, colourless, delicate, rough or granular, and re- 

 tractile. Interior of the body lined with granular protoplasm, 

 chlorophyll-cells, and refractive colourless amylaceous granules. 

 Nucleus peripheral ? Contracting vesicle also peripheral, and 

 in plurality, if certain temporary and conical projections of the 

 lorica indicate this. 



Size. Lorica T-frth of an inch in diameter ; fusiform spicules 

 5^th long ; spines y^-Trth long, and disk of same , ^ ^ „ ^ th, or 



« O ' 



twice the width of the shaft ; tentacles -o-r^th of an inch long. 



Hab, Heath-bog water. Locomotive ; progressing by means 

 of the spines, which are ambulacral, and by the tentacles (?). 

 Kind of nutriment and mode of incepting the same undeter- 

 mined ; probably in very minute portions, or by suction, as with 

 Acineta. 



Loc. South coast of Devon. 



Observations. — I have found several specimens of this Rhizo- 

 pod, one of which was one-third larger than the measurements 

 above given; some are colourless. It at first looks like a 

 spiniferous Actinophi'tjsl and not unlike the figure of A. viridis, 

 Ehr. 



Dilute sulphuric acid, followed by iodine, gives a deep claret- 

 colour to the refractive granules, and a dark brown colour to 

 the chlorophyll-cells, which are thus seen to contain a granular 

 protoplasm. Strong sulphuric acid colours the substance of the 

 tubes apparently black, but, after deepening, extracts the colour 

 of the refractive granules entirely. On the addition of more 

 iodine (z. e. iodine in solution of iodide of potassium), the dark 

 colour of the interior of the spines disappears from both ends 

 towards the centre, thus showing that the spines are hollow. 

 Neither strong sulphuric nor nitric acid dissolves the spines 

 nor the "fusiform spicules" on the lorica; while their rigid 

 nature, in addition, inclines to the view that they are both 

 siliceous. During life, the free or forked extremity of some of 

 the spines is closed and pointed. The tentacles disappear, and 

 some of the spines (which are much longer than the general 

 average in certain specimens) become detached under the efi'ect 



