78 THE KOTIFEKA. 



which, at first, I thought one of the common forms of the minuter Notommata or 

 FurcularicB. But I presently perceived that it had peculiarities of structure, which were 

 quite unfamiliar to me. Its figure is nearly that of a cylinder, somewhat bowed down- 

 ward at each end, and a little arched along the dorsal line. A small truncate foot carries 

 two slender toes, about two-thirds as long as the body, much decurved, so as to form a 

 segment of one-fourth of a circle ; these are usually carried wide apart. A large brain 

 bears a red eye-point considerably anterior to its extremity, visible only at intervals ; 

 in subsequent specimens, however, sufficiently conspicuous. 



The whole form and manners of this animal indicate its affinity with species which 

 are il-loricate. The situation, dimensions, and structure of the manducatory apparatus 

 are indistinguishable from those of Notomm. lacinulata ; yet the dorsal parts are inclosed 

 in a semi-cylindrical shell of transparent chitine, reaching about half-way down each 

 side, with a straight edge ; and cleft throughout the dorsal line, into two parallel halves, 

 moderately separated (reminding us of a Salpina, or still more of my Diplax compressa), 

 reaching to the end of the body, where each terminates in a point slightly over-arching. 

 Anteriorly this bifid carapace terminates transversely at what may be called the neck, 

 allowing the soft tissues of the head to be partially retracted for an instant, when the 

 lateral angles of the lorica are seen as two unchanged blunt points. It is remarkable 

 that, in a lateral view, the very front itself appears as if the integument were so stiffened 

 with chitine as to project both above and below in slightly obtuse points (fig. 12a). I 

 soon after found two individuals among conferva in a ditch at Coffin's Well, near 

 Torquay ; and still later in waters from many widespread localities. I find little varia- 

 tion in them. The dorsal cleft is shallow, but always visible when the animal turns. 

 P.H.G.] 



Length. Of body, ^y inch; of toes, -^ inch ; total, r } 4 inch. Habitat. Torquay; 

 Woolston ; Sandhurst ; Birmingham ; Cheltenham ; Oban (P.H.G.) : not rare. 



D. EXIGUA, Gosse, sp. nov. 

 (PI. XXII. fig. 13.) 



[SP. CH. Minute; lorica flexible, constantly thrown into folds; eye cervical; 

 toes thick at their base, less than one fourth of total length. 



On one or two occasions I had met with this little species in water sent me by Miss 

 Saunders, from a window tank in her residence at Cheltenham. I had marked differences 

 between it and D. valga, but yet set it down as that species, waiting for further light. 

 More than five months afterwards, I was examining some of the pale impalpable floccose 

 alga that grows thickly around the filaments of certain pond- weeds, originally from 

 Dundee, but which had been several weeks on my table, when I saw this little thing in 

 some number, and perceived that its peculiarities entitle it to specific rank. Though valga 

 is a small species, this is not half its size ; its proportions, too, are different. It is much 

 plumper and more gibbous behind ; the toes, instead of slender rods uniform in thickness, 

 are long cones, tapering to acute points ,and only one-third of the length of the head and 

 body. The investing integument is evidently very flexible, every contraction and every 

 turn throwing it into strong folds. Yet, thin as it is, it is a true lorica, reaching half- 

 way down each side, as in valga, and displaying the dorsal fissure quite distinctly, as 

 one views it from behind ; when it is seen to be very shallow. No other points in its 

 economy seem noteworthy. P.H.G.] 



Length, ^^ to ^ inch ; toes alone, T3 a OI j to X^UTT inch ; lorica, -5^ inch. Habitat. 

 Algffi in fresh-water aquaria (P.H.G.) : rare. 



