| OCR Text |
Show 362 PROF. W. N. PARKER ON THE [June 19, In both species distinct glands are present in the. grooves of the opercular and dorsal spines, and in the former they are very large, extending a considerable distance both above and below the spine, along the greater part of its length. The glands consist of relatively enormous granular nucleated cells, the structure of which is apparently similar in both species. Plate X V I I . fig. 1, taken from a transparent preparation, shows the general form and relations of the opercular glands. Anteriorly both dorsal and ventral portions project into the bony cavities already described as being present at the junction of spine and bony operculum. From this region each gland broadens out to form a large anterior Fig. 2. y/--.. Trachinus draco. Fig. 1. External view of tbe left opercular bone and its spine. Fig. 2. Side view of the third dorsal spine. ar. Articulation of opercular bone with hyomandibular. gr. Groove in spine. op. Opercular bone. op.s. Opercular spine. z. Conical cavities in opercular bone, continuous with the grooves of the spine. lobe, which in its widest pait consists roughly of about nine or ten irregular rows of cells. About halfway along the spine the anterior lobe gradually narrows, and ends a short distance from the projecting apex of the spine. In Plate XVII. fig. 2 a surface view of the apex of the spine is shown, indicating the manner in which it usually projects from its |
