30 
CLASS ANNELIDA. 
Hypog^on, Sav ., have an additional odd pair of seta) on 
the back of each ring : they belong to America. Hypogaon 
hirtum, Sav., Egg. Annel. p. 104. 
MM. Audouin and Milne Edwards also distinguish Tro- 
PHONIA, which have on each ring four bundles of shorter 
setae, and a great number of long and brilliant ones, which 
surround the mouth. — Trophonia barbata , Aud. and Edw. 
Littor. de la France, Annel. pi. x. f. 13 — 15. 
Nais, Linn ., 
Have the body elongated, and the rings less marked than the 
lumbrici. They live in holes, which they excavate in mud, 
at the bottom of the water, and from which they protrude the 
anterior part of their body, which they keep incessantly mov- 
ing. There are visible on the head of many some small black 
points, which may be taken for eyes. They are small worms, 
and their power of reproduction is as astonishing as that of 
the hydrm. Many of them exist in our fresh waters. 
Some have setae tolerably long, Nais Elingius , Mull. Wurm, 
ii ; N. littor alls, id. Zool. Dan. lxxx. 
And sometimes a long proboscis in front, Nais proboscidean 
id. Wurm, i. 1 — 4., of which M. de Lamarck makes his genus 
Stylaria. 
Or several small tentacula at the posterior extremity, Nais 
digitata , Gm. ; cocca 7 Mull. ib. v.; of which M. Oken makes 
his genus Proto. 
Others have very short setae, Nais vermicularis , Gm., Pees. 
III. xciii. 1 — 7 ; N. Serpentina , id. xcii., and Mull. iv. 2 — 4 ; 
Lumbricus tubifex , Gm., Bonnet, vers d’eau douce, iii. 9 — 10. 
Mull. Zool. Dan. lxxxiv. ; Lurnb . lineatus , Mull. Wurm. iii. 
4—5. 
We may approximate to this genus certain annelida hitherto 
referred to the lumbrici, which fabricate for themselves tubes 
of clay, debris, &c., in which they live, Lumbricus t-ubicola , 
