14 
Davis, on the genus (Ecistes. 
the family (Ecistina, as propounded by Ehrenberg and in- 
dorsed by Williamson and Pritchard. 
Genus (Ecistes. 
( E . intermedins (n. sp.). — Sheath granulate ; pale at the 
base, growing dark and opaque towards the open extremity ; 
narrow ; tapering slightly downwards. The simple trochal 
disc ovoid in outline, and its cilia interrupted in the dorsal 
aspect. Beneath the oral aperture a ciliated protuberance, 
on each side of which is a setiferous tubercle. Length of 
case -jV'* animal about - j y / * (PI* figs. 1, 2, 3, 4.) 
This species is plainly a connecting link between CE . crys- 
tallinus and Limnias ceratophilli , having the single trochal 
disc of one and the tapering tube of the other ; yet a strict 
reading of artificial characteristics would undoubtedly exclude 
it from either genus, and justify me in absurdly making 
another on purpose for it. Limnias requires the mature 
animal to have a “ two-lobed rotary organ/’ and (Ecistes a 
single lobe, but a “cylindrical case.” In my difficulty I 
apply for advice to our highest authority in these matters, 
and am recommended to “ call it (Ecistes, but note its resem- 
blance to Limnias.” 
CE. longicornis (n. sp.). — Sheath solitary ; rarely contiguous, 
and imperfectly conglomerate ; floccose ; generally unsymme- 
trical and opaque. Animalcule with two long antennae termi- 
nated by retractile setae ; thickly ciliated “ chin.” Length of 
case tow // 9 animal about -fe " ; antennae - 5 -^- 0 ". (Figs. 5, 6 , 7, 8 .) 
There are also two varieties of this species, one resembling 
it in every particular with the exception of the antennae, 
which are replaced by setiferous tubercles, as in CE. intermedius 
and in Limnias ; the other variety has a more cylindrical 
case, which is slightly annulated, and transparent even when 
grown in turbid water. 
I find these creatures in ponds near Leytonstone, growing 
on leaves of the water ranunculus and other aquatic plants. 
Even minute filaments of Confervae are often studded with 
their nest-like cases. CE. longicornis is by far the smallest of 
the tube-dwellers ; its brown, fluffy, and irregularly formed 
sheath is scarcely noticeable under a low power, and to this 
circumstance I attribute the fact of its being hitherto over- 
looked. The body of the animal, when the disc is retracted, 
is somewhat oviform, gradually attenuated to a highly elastic, 
deeply corrugated foot-tail. Outside the integument are four 
fine lines indicating segments of a delicate carapace ; these 
