104 THE EOTIFERA, 



C. CAUDATUS, Ehrenberg. 

 (PI. XXVI. fig. 6.) 



Colurus caudatus .... Ehrenberg, Die In/us. 1838, p. 476, Taf. lix. fig. 8. 



[SP. CH. Lorica, in dorsal aspect, pear-shaped, widest behind ; dorsal hind sinus 

 shallow, betioeen very short terminal points, not at all produced ; ventral cleft close, 

 abruptly becoming a semi-circular foot-orifice ; toes slender, frequently expanded ; foot 

 and toes three-fourths as long as lorica; eyes two. Lacustrine, 



There are several species which may, almost equally well, serve as the caudatus 01 

 Ehrenberg, to distinguish which requires minute examination. The ahove characters 

 are carefully noted from many observations, and need not be repeated. The free expan- 

 sion of the long toes, unusual in this group, is noteworthy. The frontal hook is normal, 

 and I have repeatedly seen two eyes just beneath it. On the ventral surface the abrupt 

 expansion of the fissure from a linear cleft to a broad round opening for the emission of 

 the wide basal foot-joint, should be noticed. P.H.G.] 



Length. Total ^ inch. Habitat. Birmingham ; Woolston (P.H.G.) : weedy pools. 



C. AMBLYTELUS, GoSSC, Sp. HOV. 



(PI. XXVI. fig. 5.) 



[SP. CH. Lorica, in dorsal aspect, broadly ovate, the hind ends rounded, without 

 projecting points ; ventral cleft gaping, widening before and behind ; toe single, long, 

 with a medial depression; foot and toe two-thirds as long as lorica; eyes cervical. 

 Marine. 



This species also may be very readily confounded with C. caudatus, but the cha- 

 racters above given, though minute, seem to distinguish it satisfactorily and constantly. 

 The lorica is arched, so that its dorsal outline forms about one-fourth of a circle, split at 

 its occipital end, and also for a little way above the foot ; the two lateral extremities 

 being rounded. When the animal in its turnings shows the ventral side, even though 

 slightly, we seem to see sharp points to the lorica ; but this is an illusion, for the points 

 are but the ends of the curved plates seen edgewise ; another turn, and they at once become 

 again obtuse. On the ventral surface, which is nearly flat, the edges of the two plates 

 are either wide apart or very closely approach each other, or may even overlap, but recede 

 on each side of the foot, so as to leave the orifice nearly circular. The single long slender 

 toe, running off to a fine point, has a medial mark throughout, as in those Metopidice, 

 &c., which keep the toes ordinarily appressed; but I have never seen a separation, 

 and the most delicate focusing with high powers fails to divide the fine point. The 

 usual hood is displayed. The mastax and its trophi are normal. The brain, large and 

 turbid but undefined, occupies the occiput ; and two minute red eyes, rather close together, 

 are situate on it cervically. The other interior organs are as ordinary. One oil-globule 

 (sometimes two) occupies in general the middle of the back, and is conspicuous. 



This species seems exclusively marine. I have found it somewhat numerous among 

 algfe, collected by Mr. Hood from tide-pools at low-water at Taymouth, near Dundee, 

 and also in Torbay. It is very restless, ever roaming, yet mainly affecting the conferva, 

 at which it nibbles constantly ; when swimming it shoots along with smooth rapidity. 

 The form is plump and round, the blunt corners low-descending ; the body hyaline and 

 colourless, the taper toe stretching far behind. 1 P.H.G.] 



1 I am very confident that other species of this long-toed group exist, in both our fresh and salt 

 waters. But though I have some drawings and notes, I have not as yet materials sufficient for satis- 

 factory diagnosis. P.H.G. 



