558 Transactions of the Society, 



XI. — On new species of Seyphidia and Dinophysis. 

 By J. G. Grenfell, F.G.S. 



(Bead 8th June, 1887.) 

 Plate XI. 



Last September I came across au exceedingly interesting new species of 

 Scypliidia living parasitically on the tails of some sticklebacks in Dorset- 

 shire. From its habit I propose to call it ScypJiidia amoehsea. I have 

 not yet found it on the sticklebacks near Bristol. The points of special 

 interest are two : first, the mode of attachment, and secondly the process 

 of reproduction, which has hitherto been unknown in any species of this 

 genus. Sometimes the animal is simply attached by the posterior end of 

 the body in the ordinary way, without there being anything to draw special 

 attention to this part ; as in plate XI. fig. 1, 2 ; or again the base 

 may be widened out, as in fig. 4. But in the great majority of cases, 

 the animal is attached by means of pseudopodia, as in figs. 5-10. 

 These may take the form of a single lobe or of two simple lobes, and so 

 on up to several large highly complicated processes. I found it hard to 

 draw these accurately from the living animal, because the stickleback's 

 tail interfered with the light; but by killing with salicylic acid and 

 staining I obtained a number of good specimens free. On the living 

 animal I sometimes found that the lobes of the pseudopodia ended in 

 threads, but these are not visible in preserved specimens. 



I do not know of a parallel case among the Peritricha ; but among 

 the Holotricha Stentor Boeselii sometimes has pseudopodic projections 

 round the base, according to Simroth, but mach smaller and less com- 

 plicated ones than in the present case. 



The integument of this species is highly elastic, as in the rest of the 

 genus, and the animal consequently assumes a variety of forms, as may 

 be seen in the figures. On the whole, however, the body is conical, in- 

 creasing in width from the base upwards. The surface of the integument 

 sometimes seemed highly granular in living specimens. 



The body is generally divided into two distinct portions ; the upper 

 half is very coarsely granular ; it contains the contractile vesicle in its 

 upper portion ; the lower half of the body is nearly always very much 

 clearer ; in its upper part lies the very large granular nucleus which is 

 always a very conspicuous object, is broadly egg shaped, or sub- triangular, 

 and occasionally I have seen this divided into two parts. The peristome 

 is well developed. 



I met with one live specimen in the act of dividing by transverse 

 fission. This is shown in fig. 14. A well-marked constriction had been 

 formed, and the new ciliary wreath was in active motion all round. I 

 did not trace the process further than this, but I think there can be no 



EXPLANATION OF PLATE XL 



Fig. 1-6. — Scjphidia amcehiea from the living animal. 

 „ 7-10, from preserved specimens. 



„ 11. — Scyphidia amcebxa dividing ; from the living animal. 

 „ 12. — Dinophysis semicarinata. 



