| OCR Text |
Show 82 MR. F. E. BEDDARD ON AN ANNELID [Feb. 5, which it will be seen that a semicircular depression with the concavity directed forwards is the external m anifestation of the organ, of which the mass of cells lie behind. In a specimen in which the prostomial organ is lateral in position (text-fig. 8,B), an external depression is to be seen with equal clear- A Text-fig. 8. B Bothrioneuron iris. Fig. A. Prostomium from below. Fig. B. Ditto from above. S, sense-organ symmetrically placed in A, asymmetrically in B. Text-fig. 9. Bothrioneuron iris. Longitudinal section through the prostomium. S, sense-organ ; B, supra-oesophageal ganglion. uess, but naturally in profile. In a longitudinal section (text-fig. 9) of a specimen in which the sense-organ happens to be median and quite anterior in position, the following appearances are observable : the supposed sense-organ consists of a mass of cells which are rather deeperthanare thoseof the surrounding epidermis ; this is especially |
