326 On Species of Squamulina and Difflugia. 



the neck while living, and the animal substance forced out by 

 pressure, showing that it is composed of : — «, granular sarcode ; 

 b b, oil-globules ; ccc, reproductive cells about 2^-6000ths of an 

 inch in diameter ; d, disk of Mclosira. 



N.B. All the parts of this figure are relatively magnified on a 

 larger scale than the foregoing, viz. on that of l-24th to l-6000th 

 of an inch. 



Plate V. 



Fiy. 1. Sqiiamulina varians, mihi, greatly magnified, to show the struc- 

 ture and cavity of the test ; elevated convex form, lateral view : 

 a, body ; b, expanded margin of the disk by which it adheres to 

 the fucus ; c, aperture ; f/, dotted line indicating the form of the 

 chamber; e, projecting ends of spicules. Height of body about 

 l-69th of an inch, base about l-54tli of an inch in diameter. 



N.B. This and the three following figures (viz. 2 to 4 inclu- 

 sively) are strictly drawn upon the same scale && S. scopula (viz. 

 l-24th to l-1800th of an inch), to show the relative size of the 

 coiTesponding parts in each species (S. varians corresponding to 

 the pedestal of S. scopula) and of their ovra parts individually, 

 latitude of delineation only being allowed, as in S. scopula, to 

 the spicular detail. 



Fig. 2. The same, discoidal portion of fig. 1, showing : — a, expanded 

 margin ; b, dark shade indicating width of wall and attachment 

 of body to disk ; c, dark line indicating chitinous lining ; d, cen- 

 tral or internal portion of disk ; e, aperture. 



Fit/. S. The same, outline of a disk showing, by the pseudo-septal pro- 

 longations, a tendency to trilocular division : a, expanded mar- 

 gin ; b, central or internal area of disk ; c c, pseudo-septal pro- 

 longations ; d, aperture ; c, chitinous lining of chamber. 



Fiff. 4. The same, outline of a disk showing a tendency to multilocular 

 division : a, marginal expansion ; b, central or internal area of 

 disk ; ccc, pseudo-septal prolongations of the test, causing the 

 basal outline of the chamber to assume a crenulated appeai'ance ; 

 d, aperture; e, chitinous lining of chamber: /, disk oi Melosira, 

 relatively magnified. 



Fig. 5. The same, amoeboid form of test : a, aperture. (Scale l-48th to 

 l-1800th of aninch.) 



This figure, on half the scale of the foregoing, is to show the 

 extreme variation of form, in this species, wliich may exist be- 

 tween the simple, symmetrical, dome-shaped figure 1 and the 

 amoeboid form, figure 5. 



Fig. G. Diffiugia bipes, mihi, outline of test, with animal in the interior, 

 greatly magnified : a, test ; b, animal ; c, pseudopodia ; d d, con- 

 tracting vesicles ; e, nucleus ; /, oil-globules and other reproduc- 

 tive (?) cells ; g, fragments of incepted food ( Algre) ; h, sarcodal 

 retractile filaments. (Scale l-24th to 1-GOOOth of an inch.) 



Fig. 7. The same, test empty, showing uniformity of arrangement in the 

 scaly covering ; also, a, circular line indicating form and position 

 of animal when suddenly retracted. Greatast length of test 

 33-6000ths of an inch, greatest width 17-6000ths. 



Fig, 8. The same, test empty, lateral view : a, imaginary position of 

 pseudopodia. 



Fig. 9. The same ; scales more magnified, to show their circular form 

 and mode of arrantrement on the test. 



