In a memoir on the organs of sense in the Annelids (Ann. d. Sc. Nat., Зe Serie, t. xiii), I designated, under the name of Torrea vitrea, a worm remarkable for the complex nature and the development of the eyes, and the extreme transparency of the tissues. Owing to this favourable circumstance, as well as to the unusual size of the spermatogenous masses, I was enabled at once to observe in it phenomena, of which I have spoken in a note annexed to the report of Milne Edwards on the results of his travels in Sicily (Ann. d. Sc. Nat., Зe Serie, t. iii.), and concerning which I shall now enter more into detail.