Microscopical Society. 2 1 27 



A paper by George Busk, Esq., being ' Observations on the Shepherd's Purse Co- 

 ralline of Ellis — the Notamia Bursaria of Fleming,' was read. The author com- 

 menced by stating, that nearly all the modern descriptions of this zoophyte were taken 

 from that given in a work published in 1755, by Mr. Ellis, who appears to have been 

 the first who noticed it. This description is, however, incorrect; and consequently 

 those founded upon it must be considered equally, if not more so. This he stated to 

 be the more remarkable, as the zoophyte is by no means uncommon on the south coast 

 of England, particularly in the neighbourhood of Swanage, in the Isle of Purbeck, 

 where it appears to live and flourish in from five to ten fathoms water, throughout se- 

 veral miles of the coast, extending from that place to Bournemouth. This zoophyte, 

 according to Mr. Busk, consists of a creeping, tubular, radical portion, from which 

 the celliferous or polypi ferous branches arise. This radical part is composed of a cen- 

 tral discoid portion, not unlike the body of an Ophiura, with branches radiating from 

 its periphery, and creeping, in a nearly straight course, over the surface of the object 

 upon which the zoophyte is growing. Besides these radical tubes, celliferous branches 

 occasionally arise from the disc itself. The disc and its branches are both formed of 

 a thick, firm, horny envelope, containing a coarse granular matter, of a yellowish 

 white colour. These radical tubes give off, at irregular distances, secondary branches, 

 which soon terminate in the celliferous portion. Each of these secondary branches, 

 however, arises from a distinct compartment, formed by a thick septum, which shuts 

 off the opening of the lateral branch from the main cavity of the parent tube. The 

 celliferous branches are dichotomously divided at pretty regular intervals. At each 

 bifurcation, one of the branches has usually three pairs of cells superiorly and one 

 single cell below, while the other has but two pairs of cells above and one below ; but 

 this arrangement is not constant in all specimens. The cells are of two kinds, — a 

 smaller sort, like short tobacco-pipes, and a larger, which are the polypiferous cells. 

 The walls of the smaller cells or cups are tolerably thick, but brittle and opaque, from 

 the quantity of calcareous matter they contain. The mouth has a sinuated margin, 

 which rises anteriorly into a sharp curved beak, like that of the cuttle-fish, which is of 

 a horny nature. In each cup there is also a moveable beak, which opens or closes the 

 aperture, as may be required : these two beaks constitute an admirable instrument for 

 prehension, and that such is their office is rendered probable by the existence of mus- 

 cles, by which they are moved. This beak or mandible during life opens suddenly 

 with a sort of snap, and is closed slowly. The muscles exhibit transverse stria?, and 

 thus approximate to those in the higher classes of animals. The polype cells are 

 many times larger than the cups : they are closed at the top, and, contrary to what is 

 stated in all previous descriptions of this zoophyte, there is no connexion whatever be- 

 tween these cells and the cup-like cells placed immediately above and behind them. 

 The orifice of the cell is on the anterior face, is of a crescentic form, and its lips ap- 

 pear to be strengthened by a thin band of horny material : it contains an ascidioid 

 polype, having ten tentacula and no gizzard. The mode of interconnexion of the 

 various parts of the polypidom was shown, and the margin which the polypiferous 

 branches originate explained by reference to figures and diagrams. The author ob- 

 served, that in the course of his examination of other species of Bryozoa, he had also 

 observed the striation of the muscular fibre in several, and thence concluded that it 

 would be found to be generally the case in that class of animals. 



