SPIRORBIS GRANULATUS. 405 
Habits.—It is very hardy in confinement, living far from the sea in a shallow glass vessel 
for months, a little fresh water being added to the sea water at intervals. The stones to which 
the tubes were attached were covered with Clava multicornis. So sensitive are the annelids 
that they dart inward on the approach of a foreign body. At intervals small pale masses 
are ejected from the tubes, being the ejectamenta from the rectum propelled forward by 
ciliary action and perhaps by a jerk of the tail, as stated by Dr. Willams, since it frequently 
jerks the posterior extremity when removed from its tube, though no débris was observed 
issuing on these occasions. 
Reproduction—tIn this species (March Ist) the ova lie along the intestine—some op- 
posite the stomach, others behind, and thus they differ in position from those of S. borealis, 
which lie chiefly posteriorly and tint the region reddish. In the first week of March the ova 
are larger than those of S. borealis, and, in confinement in the laboratory, they are larger 
than in those fresh from the rocks. On breaking open the tubes of those in confinement in 
June a number of salmon-coloured ova were found toward the smaller end. They were 
firmly attached by an elongated hyaline process to the inner surface of the tube (Plate CX XII, 
fig. 7e). In each string are about thirty ova arranged for the most part in a double row, 
and all contamed embryos which showed very active ciliary motion at one end like the 
embryos of Doris. A single free cell often accompanied the embryo (Plate CX XII, fig. 7/f), 
which, when liberated, swam by aid of the cilia. Several free larvee (Plate CX XII, fig. 7g) 
also occurred in the vessel, presenting the usual trochophore outline, viz., an ovoid body and 
a ciliated ring (prototroch), part of the body in certain positions projecting beyond the ciliated 
ring. Two eye-specks are present (Plate CX XII, fig. 7h). A posterior bristle or two appear 
in front of the posterior end, and one or two pairs of the anterior bristles also occur. 
Moreover, breeding appears to have gone on for some time, since the stones in the vessel 
have numerous minute tubes just visible to the naked eye, and the contained forms are not 
fully developed (Plate CX XII, fig. 7). The tube at this stage appears to be smooth. The 
branchiz are only sparsely divided, each filament having two richly ciliated pimne (6, 6) 
and a non-ciliated terminal process (a). The pinne are capable of various movements, have 
mucoid hypodermie cells, and their cilia are somewhat longer than the diameter of the pinne. 
The operculum seems to be a hollow process, with a calcareous concretion (e) in the enlarged 
region below it, and this is readily fractured under pressure. Bristles are now developed, 
and have in miniature the characteristic outlines of those of the adult. The colour of the 
young form with its opercular stalks is pinkish by transmitted light, the branchize being pale. 
The tubes are coiled like rams’ horns, or simply curved, and a few are elongate-spiral, like 
an Indian antelope’s horn. Some of the tubes were empty or tenanted only by Diatoms, 
so that even at this early stage enemies destroy them. 
On the whole, comparatively little change takes place in the development of this 
species. ‘The eyes may be of use to it in its pelagic existence and in selecting its site ; they 
then disappear. The anterior portion develops into the operculum, the branchie budding 
from the opposite side of the same region, whilst the bristles appear, and the secretion 
of the minutely granular tube goes on. The oil-globules in the embryos are of a rich 
salmon-colour. 
The tube (Plate CX XXII, fig. 5d) is sinistral, turning from right to left, and strongly 
erooved—making in large forms three conspicuous ridges. When on a clean surface of 
