1869.] and Memlranipora Bengalensis. 87 



contain the so-called suckers ; these becoming more distinctly ap- 

 parent in the contracted position of the animal, (see fig. 4, pi. X). 

 These suckers, however, are not essentially characteristic, and ap- 

 pear to vary greatly with the age. Along the dorsal edges of the 

 septa, there seem to be also some longitudinal fibres present. This 

 second layer is the same which, in several Actiniacea, becomes coriace- 

 ous, taking a principal part in the formation of the exotlieca of other 

 corals. The third layer (y) only consists of thick, transverse fibres, 

 containing large, dark green pigment cells. Below this follows 

 a tough muscular tissue (8) consisting of thin longitudinal and much 

 stronger concentric fibres, gradually passing into a regular carti- 

 lagenous skeleton (e), composed of an intercellular substance, and a 

 large number of various scleroid particles ; the figures 5, 5a, bb and 5e, 

 on plate XI will illustrate this. Figure 5 represents a small portion 

 of the fourth layer, the three upper ones having previously been 

 removed by maceration. The muscular fibres are especially strong on 

 a portion of the septum ; the cinciides are spacious. Fig. 5a repre- 

 sents the reverse or internal side of the same portion of the integu- 

 ment, and shews on the surface an irregular distribution of the scleroids. 



The two last layers (8 and e) chiefly compose the mesenterial septa, 

 extending above to the mouth and at the base up to the centre, but 

 being on the internal edge along the central axial cavity deeply insinu- 

 ated. The hardest portions of the septa are those round the larynx and 

 at the base, evidently on the two places where the strongest muscular 

 actions are required. In figure 3, pi. XI the most cartilaginous 

 portions are indicated by cross lines. 



It is usually stated that the Halirhoda, and especially the 

 Actiniacea have neither an internal, nor an external solid skeleton, 

 and this notion gave rise to the name Hexacorallia tnalacoder- 

 mata. There can be, however, no doubt that in the present case 

 the two internal layers, as represented on plate XI, figures 3 and 

 5, correspond to those which - in the Astr;eacea for instance - 

 secrete the enthotheca. The scleroid particles are of two kinds ; 

 some of them are long, with slight lateral appendages, and others 

 simple, sharply angular flat bodies, as shewn in figures 5b and 5c on 

 plate XI. These scleroid particles are only visible when enlarged 

 to about 500 diameters ; and some of them arc still extremely 



