DINOCHARID^l. 78 



This Dinocharis was discovered by Dr. F. Collins in 1866, in a small pool in a wood 

 near Sandhurst. Dr. Collins sent it to Mr. Gosse, who figured and described it (loc. cit.) 

 in 1867. Dr. Max. Perty's Polychatus subquadratus may possibly, but not probably, be 

 the same creature ; if so, it is most inaccurately drawn and described. Mr. Archer's 

 Polychcetus spimilosus is undoubtedly D. Collinsii. 



Mr. Gosse says of its habits that "it is rarely still, rooting among the sediment or 

 swimming with a smooth gliding motion of no great speed. If I may judge of its be- 

 haviour in freedom from what is seen while under our notice, it seems to be a specially 

 bottom-frequenting form." 



Length, -^ inch. Habitat. Sandhurst, Berks (Dr. F. Collins); Clifton (Mr. 

 Brayley) ; Carrig and Gallery districts, Ireland (Mr. T. Archer) ; Dundee (P.H.G.) : rare. 



Genus SCAEIDIUM, Ehrenberg. 



GEN. CH. Lorica vase-shaped and compressed ; or pear-shaped and depressed in 

 front ; very thin, transparent, smooth, without spines or projecting plates ; head with 

 a chitinous cuticle, except in front ; eye single, really or apparently attached to the 

 mastax ; foot without spurs ; toes very long. 



In the genus Scaridium the foot and toes (especially the latter) are remarkable for 

 their great length, for the distinct condyles, which give them such free action, and for 

 the powerful striated muscles, which enable the animal to jerk its long toes widely 

 apart, and to strike the water violently with its foot, so as to make it an effective organ 

 of locomotion. In both species the lorica is a transparent, thin, stiff skin, which ap- 

 pears to be continued over the foot ; but its shape in the two species is very different : 

 for, while the lorica of S. longicaudum recalls that of Dinocharis pocillum, the lorica of 

 S. eudactylotum somewhat resembles in general outline that of a Brachionus. In each 

 species the eye appears to be attached to the mastax, instead of to the nervous ganglion ; 

 this would be a very unusual arrangement, but it is possible that the appearance is due 

 to the nervous ganglion's being closely applied to the mastax, and more than usually 

 transparent. 1 The habits of the two creatures are similar. They swim quietly for a 

 time, trailing the foot and toes behind them in an elegant curve ; and then, with a 

 sudden leap, they dart off into a new course. 



S. LONGICAUDUM, Ehrenberg. 

 (PI. XXI. fig. 5.) 



Scaridium longicaudum . . . Ehrenberg, Die Infus. 1838, p. 440, Taf. liv. fig. 1. 

 Gosse, Phil. Trans. 1856, pi. xvii. figs. 64, 65. 



[SP. CH. Body compressed ; front truncate; eye adherent to mastax ; body, foot, 

 and toes of about coequal length. 



The most remarkable peculiarity of this species is the anomalous character of the 

 eye, a large flattened capsule, with crimson pigment not jjuite filling it, permanently 

 attached to the surface of the mastax, and apparently not connected, as usual, with the 

 occipital brain, which, however, presses upon it from above and behind. The trophi, 

 too, are very abnormal. (See my Mem., loc. cit.) The animal, with its long unwieldy 

 foot and toes, reminds us, not less by its movements than by its form, of Dinocharis. 

 It is active, swimming with unequal, not very swift, action, with little movement of the 

 foot and toes. It has the habit of making sudden springs, using, apparently, for this 

 purpose, the fore parts, not the toes. P.H.G.J 



1 I suspect this to be the case in S. eudactylotum ; but in S. longicaudum Mr. Gosse is confident that 

 ihe eye is inseparably seated on the mastax. 



