2Q 77/6' Structure of Dictyosphceria. 



probably equally tenable that the cells immediately overlying and under- 

 lying the cells of the middle layer are merely spaces enclosed by mem- 

 branes separated from the wall of the middle layer by the growth of the 

 bordering cells, and now suspended, as it were, from one border to the 

 other. In favour of this latter view, I should state that I have never seen 

 any cell contents in these overlying and underlying spaces, while those are 

 plentiful, but disorganized, in the cells of the middle layer. Where the 

 section has run along a row of bordering cells, the appearance seen at a 

 (fig. 7) is presented. I account for the appearance at b by supposing 

 that it is an intrusion from the bordering cells, or more probably a cut-off 

 angle from an adjoining cell of the middle layer. Owing to the condition 

 of the material, which required very careful treatment to enable me to 

 obtain this much information, I have been unable to carry the 

 investigation of this species farther. It suffices to show us a form 

 differing very strikingly from the simple D. favulosa, and probably 

 confirming the view taken of the affinity of the genus with Anadyomene 

 a view much shaken by the examination of D. favulosa. I have to 

 thank Miss Mitchell for sketches of tenacula in the accompanying plate, 

 and for the interest she has taken in Dictyospkaeria. 



GEORGE MURRAY. 



EXPLANATION OF PLATE VI. 



Fig. i. D. favulosa in various stages of development; a, c, d, e ( x 2) ; b ( x 8) ; 



f, nat. size ; g, in section ( x 3) ; a and b represent a plant 



consisting of a single cell ; in b, tenacula have already been 



developed. 

 Fig. 2. ,, Cells joined by tenacula, diagrammatic view. 



(a) alternate tenacula joining two cell-walls ; (b) tenacula 



seen from below; (c) seen from above ( x 150). 



Fig. 3. Tenacula from internal cells side view ( x 150). 



Fig. 4. Internal projections from cell-wall ( x 150). 



Fig. 5. D. sericea, surface view ( x 66). 

 Fig. 6. Bordering cells with tenacula ( x 375). 



Fig. 7. ,, Section of thallus ( x 66). 



Fig. 8. Nat. size. 



