32G 0)1 Sj)ccies of Stiuaiinilina (n)(? Difflngia. 



tlu' nock wliilo liviiifr, and tln' imiinal substance forced out by 

 pivssinv, showing' that it is composed of: — </, <,^raniilar sarcode ; 

 /) b, oil-gl<ibiiles ; c c c, reproductive cells about 2^-GOOOths of an 

 inch in diameter ; d, disk of Mc/osira. 



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

 larjrcr scale than the foregoing, viz. on that of l-24th to 1-GOOOth 

 of an inch. 



Plate Y. 



Fit/. 1. Sqiiamtiiina van'ans, mWn, greatly magnified, to show the struc- 

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

 (I, body ; b, expanded margin of tlie disk by wliich it adheres to 

 the fucus ; c, aperture ; <l, dotted line indicating tlie form of the 

 chamber: c, projecting ends of spicules. Height of body about 

 1-OOth of an inch, base about l-54th of an inch in diameter. 



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

 sively) are strictly drawn upon the same scale as 6'. scopida (viz. 

 l-24th to 1-I800th of an inch), to show the relative .size of the 

 con-esponding parts in eacli species ( <S'. variaim corresponding to 

 the pedestal of S. scopida) and of their own parts individually, 

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

 the spicular detail. 



Fit/. 2. The same, discoidal portion of fig. 1, shownng : — a, expanded 

 margin ; i, 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/. ;'.. The sami', 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 ; e, chitinous lining of chamber. 



Fit/. 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 appearance ; 

 d, aperture; e, chitinous lining of chamber; /, disk of Mehsi7-a, 

 relatively magnified. 



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

 l-1800th of an inch.) 



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 

 amojboid form, figure 5. 



Fiff. 0. Diffiiii/iti bi/)t's, mihi, outline of test, with animal in the interior, 

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

 tracting vesicles ; e, nucleus ; f, oil-globides and other reproduc- 

 tive (?) cells ; ff, ii-agments oi incepted food (Alg£E) ; h, sarcodal 

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



Fiff. 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. Greatest length of test 

 3.3-(KX)0ths of an inch, gi-eatest width 17-GOOOths. 



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



f)3eudopodia. 

 10 same; scales more magnified, to show their circular form 

 and mode of arrangement on the test. 



