80 THE ROTIFERA. 



the skins of decaying algae, and other aquatic plants. It seems reluctant to swim in 

 the open water ; but yet can glide along, smoothly and swiftly, when it pleases. 



Three months had nearly passed, and I had met with no second example of this 

 beautiful species, though examples of valga and semiaperta had been numerous. But 

 then, in water from the same fruitful pond at Woolston, a specimen occurred, which 

 seemed the counterpart of pata, except that the great brain was destitute, so far as I 

 could discern, of the pink eye, which had been the most conspicuous distinction of the 

 species. Presently, however, another appeared ; and here the whole occiput was 

 instantly seen to be radiant with the soft, rose-red tint ; the eye, in fact, or at least its 

 pigment, occupying, just as in my first example, the whole lower part of the ample 

 cerebral sac. Hence I infer that the rosy hue, normally pale, may sometimes become 

 so dihite as to be practically undiscernible. P.H.G.] 



Length, -^\^ inch. Habitat. Woolston Pond ; Sandhurst, Berks : rare (P.H.G.). 



D. SEMIAPEBTA, GoSSC, Sp. HOY. 



(PI. XXII. fig. 10.) 



[SP. CH. Body compressed, highest behind ; lorica with the dorsal cleft closed in 

 front, gaping behind, the ventral edges apparently approximate ; eye frontal; toes long, 

 slender, recurved. 



In describing Furcularia gibba (supra, ii. 43) I have spoken of the resemblance borne 

 to that species by the present, a resemblance which extends to other species. 



D. semiaperta bears much likeness to D. pceta, but is still larger ; it is, too, higher 

 behind, and the brain has no pink colour. There is, indeed, a well-defined oval eye, 

 of deep red hue, but of moderate size, and situate near the front (fig. 106). The 

 brain is large, descending far down the back of the neck, quite clear, and strongly 

 defined in outline. The locomotive cilia appear set on minute eminences over the whole 

 rounded front, making no wheels, but visible as a simple fringe. The trophi are 

 unusually large (fig. Wd '). The lorica, though split all down the back, has the edges of 

 the fissure in contact at first, so that only the hinder half is open, and this but narrowly. 

 In a succession of fair views that I had of one which was dying, looking down the back 

 from the front of the head, not only was the gape of the lorica well seen to be but partial, 

 but it evidently appeared that the cleft part was not elevated into a ridge, as it is in 

 other species. The lorica-halves appear even to approach along the belly, as they do 

 along the back. But I am not certain of this. Each division terminates behind in 

 an obtuse, slightly-decurved point (fig. 10), often obliterate. 



One individual of this species had two globose bladders protruding from the cloaca, 

 as I have described in D. pata. It may indicate a prevalent form of disease in the 

 genus. In one specimen was a large dark egg, nearly matured. Another had the 

 alimentary canal greatly distended, and of a greyish-blue hue, an unusual colour in 

 Rotifera ; but the mystery was explained by the fact that a colony of the Blue Stentor 

 (S. cceruleus) was established on the same sprig of water-moss ; and it became evident 

 where the Diaschiza had obtained its dinner. P.H.G.] 



Length. Total, -y^ to ^ inch. Habitat. Cheltenham ; Woolston, numerous ; 

 Birmingham ; Stormont Loch, Scotland (P.H.G.) : pools, rather common. 



1 This drawing was made from a protracted and excellent observation of a recently dead specimen, 

 completed without any reference to my published figs. (Phil. Trans. 1886). Yet it is seen how exactly 

 the details agree with those figs. (35-40), and especially with 39 and 40 of the Memoir. In examining 

 many dead specimens of D. semiaperta, I have obtained accurately the appearance of fig. 37 ; the long 

 produced, decurved points of the incus explaining what had seemed so inexplicable in situ. I am, 

 however, almost sure that these arching points proceed from the fulcrum between the rami, and are not 

 prolongations of the wide glassy rami themselves. 



