Nothing whatever appears to be known relative to the mode of reproduction of these Annelids. I have paid much attention to the subject, but as yet have not gained any positive information regarding it. The only fact which I consider worthy of being chronicled is the following: On one occasion, when quite a novice in Marine Zoology, while observing a beautiful group of Serpulæ seated on a stone, I saw issuing from out one of the tubes a kind of very fine dust, of a rich crimson hue, which continued to arise for nearly an hour in spite of repeated efforts to disperse it by aid of a camel-hair pencil. At first I believed the 'dust' to be the 'remains' of a deceased serpula, but afterwards found that such was not the case, the annelid being alive and healthy. Never having seen the phenomenon since, it has been a great source of regret to me that I did not endeavour to discover what the dust was composed of; but have little doubt that the microscope would have shown it to be, in reality, the ova of the Serpula. Another class of Annelidans, termed Sabellæ, like the Serpulæ, also build habitations for themselves, but not of the same materials. Instead of being white, the tubes of the first mentioned animals are brown in colour, and composed of minute granules of sand, or small shells, and lined internally with a gelatinous substance exuded from the body of the worm. On the interior of the oyster and other shells, and even in univalves occupied by the Lobster Crab, various tubes of Sabellæ may often be seen. They are, however, generally discovered congregated together, forming a kind of honeycomb mass in the fissures of rocks, or against the sides of rock-pools, or on the surface of small stones, &c. A mass of Sabellæ tubes forms by no means an inappropriate or unpleasant object for the tank, as the animals are hardy, and will live for many months if the water be kept pure. Moreover, while in confinement, they do not live in luxurious indolence, but ever seem to be busy in the exercise of their architectural propensities, making alterations, repairing damages, or otherwise 'sorting' their tubiculous habitations. 'The tubes of the Sabellæ,' says Dr. Williams, 'are soft, flexible, and muddy. Slimy mucus furnished by the integumentary glands of the body is the mortar or cement, fine sand molecules are the "stones" or solid material of the architecture. In the Sabellæ the lime of which the tubes are built is held in solution in the mucus provided by the cutaneous glands. It is adjusted in the fluid form, and moulded by appropriate tools into the required shape. It then _solidifies, too, under water_, like the "Aberthaw lime." The tube of the Sabellæ fits closely round the body of the worm; it is slightly elastic, and the interior is smooth.' CHAPTER XXIII. The Solen, or Razor-Fish 'His mansion he extends, So well concealed beneath the crumbling sands.' XXIII.