On the Anatomy and Histology of the Land-Planarians of Ceylon; With Some Account of Their Habits and a Description of Two New Species, and with Notes

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1874. Excerpt: ... termination of the sheath of the pharynx. The muscular attachment of the pharynx to the roof of its sheath is confined to the region immediately surrounding the tube by which it leads into the digestive tract, and it is thus anterior to the middle of the organ, and forms a sort of pedicle. The oral aperture lies immediately over the centre of the pharynx. In Bhynchodemus the pharynx has the form of a cylinder directed anteroposteriorly, and narrowed in front and behind, and which may thus be said to be caskshaped ("doliiformis" Stimps.). The pharynx is perforated in the direction of its length by a tube which runs directly into the digestive tract, entering it by an aperture having the same relation to the sheath of the pharynx as in Bipalium. The pharynx is attached to its sheath only at its anterior extremity. The cylindrical form of pharynx is evidently the older and simpler one, and is that invariably possessed by the lower Khabdoccele Planarians. The folded mouth of Bipalium is to be regarded as a modification of that of Bhynchodemus, the mouth of the cylinder having been gradually spread out until the whole organ became a flattened sucker, which, when retracted and packed away, assumes the form shown in the figure. Regarding this as being the case, and considering therefore the long irregular slit between the lips of the pharynx of Bipalium to be homologous with the rounded aperture at the extremity of the cylindrical pharynx of Bhynchodemus, the muscular arrangement in the two cases will be found to be identical. The pharynx is built up of an internal and an external set of longitudinal and circular muscular fibres, which muscular masses are connected by transverse fibres, in the interstices of which is a quantity of glandular matter. The outer mus...