Chap. I. HISTOLOGY OF CORYNE MIRABILIS. 205 



The inner wall is made up of large cells, of varioiis shapes, according to their 

 position in the animal. Low down in <ihe stem (PI. XX. Fie/. 2) the brown cells 

 of the digestive cavity cover this wall so thickly, that the cells cannot be dis- 

 covered very distinctly; but at the neck, which is, comparatively, quite transparent, 

 they may be made out with considerable clearness. Here they are curiously curved, 

 prismatic, wedge-shaped cells (PI. XP. Fiff. U, d e; PI. XXIIP. Fiff. 12, d e; PL XIX. 

 Fiff. 4, a), with their narrower ends inward, and each one occupying the whole 

 thickness of the wall. Their outer, broader ends, do not conform to the inner 

 surface of the outer wall (PI. XP. Fiff. 14, b; PI. XIX. Fiff. 4, l>) ; but each one is 

 more or less rounded, so as to leave interspaces between them and the aforesaid 

 wall. In the head these cells are much larger (PI. XIX. Fiff. 2, a a}), and have 

 straight parallel sides above and below; but, like all cells which converge around 

 a central axis, they are wedge-shaped laterally. Their outer ends {Fiff. 2, «') have 

 an irregularly polygonal shape, and overlap each other Avith lateral expansion. 

 Like those in the neck, they have very transparent, homogeneous contents, and do 

 not appear to be mesoblasted. The red, granular lining of the digestive cavity and 

 the stem, consists of very irregular cells (PI. XP. Fiff. 14 ; PI. XXIIP. Fiff. 12, d d), 

 which project their tail-like prolongations between the rounded ends of the cells 

 of the inner wall; they contain a lai'ge, irregular, dark mesoblast, which seems 

 to be the cause of the color in this lining. 



The ceUs of the inner, or axial wall of the tentacles, meet in the centre, and 

 form a double row (PI. XIX. Fiffs. 2, a% and 3, a d). When seen under a low 

 magnifying power, they appear like transverse partitions, in the axis of the tentacles 

 (PL XVII. Fiffs. 11, t, and 11"); Init a closer examination with highly magnifying 

 powers shows them to be arranged in two rows, one above {FiffS. 2, a^ a\ and 3, i) 

 and one below {Fiffs. 2 and 3, a). At the base of the tentacles there is, often- 

 times, an irregularity in their arrangement, sometimes one cell and sometimes three 

 occupying the axis; but this is owing to the fact that the inner walls of the 

 head and tentacles pass gradually into each other, so that there is no dividing line 

 between the two. The thick, irregular column {Fiff. 2 and 3, ff) running along 

 the middle of the tentacles, as seen laterally, is the double wall, formed by the 

 meeting of the cells of the upper and lower sides. The mesoblasts of these cells 

 appear like coarse, irregular granules, imbedded in the double walls at their line 

 of junction. In the perpendicular -plime of the axis the walls of the cells meet 

 each other in such a manner as to form uniform lines, from the upper to the 

 lower side of the tentacles {Fiff. 2); but, at the surface {Fiff. 3), they often meet 

 with opposite curves, or at broad angles. 



The horny sheath (PL XVII. Fiffs. 2, s, 9, c, 11, c, and 15, c; PL XIX. Fiffs. 2, 

 c, and 4, c; PL XX. FiffS. 1, a, 2, c, 3, c, and 6, e c') is composed of irregular con- 



