The chief points which are new or noticeable about Microchseta are as follows:
(1) The small prostomium.
(2) The numerous annuli that make up a somite, more especially in the case of the anterior somites.
(3) The small size of the setæ, relative to the size of the worm.
(4) The large size of the nephridiopores, and their arrangement in a line with the lateral setæ.
(5) The very large size, and complicated structure, of the nephridia themselves.
(6) The excessively strong septa of the anterior somites, being much thicker than those figured for other large Earthworms.
(7) The great number and small size of the spermathecas.
(8) The position of the spermathecae behind the other genital organs, and the presence of more than one pair in a somite.
(9) The intestinal gland in somite IX, with a structure similar to that of the calciferous œsophageal glands of Lumbricus agricola.
(10) The bifurcation of the dorsal trunk in each of the anterior somites (IV to VIII), and the union of these divisions before passing through the anterior septa of these somites.
(11) The great enlargement and thickening of the wall of the dorsal vessel in somite VIII.
(12) The curious structures, with unknown function, in somite XII.
(13) The position of the supra-pharyngeal ganglion in the somite 1.
(14) The absence of a sub-neural blood-vessel.