. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. b86 C1RRHOPODA. Fig. 337. Fig. grooves are very strongly marked in some spe- cies, as in Balanus Spinosus (Jig. 337), where the tubes are large, and the walls comparatively thin. In all they run in straight diverging lines from the apices of the compartments to their bases. There they open close to the margin of the general base. In most species, however, their orifices are, in part, filled up by an extension of the base (a, Jig. 338). In some small species, the tubes of which are wider than those of larger ones, t
. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. b86 C1RRHOPODA. Fig. 337. Fig. grooves are very strongly marked in some spe- cies, as in Balanus Spinosus (Jig. 337), where the tubes are large, and the walls comparatively thin. In all they run in straight diverging lines from the apices of the compartments to their bases. There they open close to the margin of the general base. In most species, however, their orifices are, in part, filled up by an extension of the base (a, Jig. 338). In some small species, the tubes of which are wider than those of larger ones, there is hardly any opening discoverable externally, or at most a very narrow fissure just around the margin. Very near their terminations on the mar- gin, these tubes of the diploe are joined by the very short canals which proceed from the inner circumference of the base (b, Jig. 338), and it is at their junction that the grooves in the walls of the partitions are most obvious. These two sets of tubes communicate freely all around the margin with the diploe of the base. All the Btilanids—with the exception of the Coronules—have calcareous bases. The struc- ture of the base differs from that of the walls in being composed internally of large oval cells irregularly arranged. These cells seem to communicate freely with one another and with the tubes of the valves. The Coronules have no base : their soft parts are in immediate contact with the integuments of the living animals in which they are generally imbedded. The form and arrangement of the opercule vary. There are generally four triangular valves, two larger than the others, all deeply grooved on their upper surfaces by the lines of growth. These valves cover more or less completely the soft parts beneath, to which they are attached, so as to be very moveable one upon the other, and to admit of the pas- sage of the feet through the slit that exists be- tween the two pairs. In some of the coronules, the greater part of th
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