INTRODUCTION. XX111 



tissues, and in different regions of the body. They abound 

 in the walls of the tentacles, in the marginal spherules (of 

 Actinia proper), in the corrugated integument that sur- 

 rounds the mouth, in the walls of the stomach, and in the 

 epidermic mucus that is thrown off from these last-named 

 parts on the stimulus of irritation. But there are certain 

 special organs in which they are crowded to an extraor- 

 dinary degree, and which, so far as I know, have no other 

 function than that of being magazines of the cnidce. These 

 organs are of two kinds, which I hare designated respec- 

 tively as craspeda, and acontia. 



The Craspeda. The peritoneal membrane of the septa, 

 having formed, by the contact of its two lamina?, a kind of 

 mesentery, separates again to inclose the ovary; again 

 unites into a second mesenteiy, the edge of which is greatly 

 puckered, and thickened in the form of a cylindrical cord, 

 closely resembling the bolt-rope of a ship's sails, or still 

 more the cording in the hem of a flounced garment. This 

 marginal cord, bound throughout its length to the ovary, or 

 to the septum, by a mesentery, I call the Craspedum 

 (Plate XI. fig. 2). 



So far as my examinations have gone, the craspeda are 

 found in all Actinaria, and for the most part in great 

 profusion. In T. crassicornis, for instance, they constitute 

 an inextricable tangle of white frilled cords, seen every- 

 where below and behind the stomach, and protruding 

 through every wound of the integuments. The thickness 

 of the cord does not, as has been stated, " increase from 

 above downward." Nor does it "terminate in the coats of 

 the stomach :" if we gradually cut away the stomach, piece- 

 meal, until the free edge has disappeared, we still find the 

 craspeda bordering the mesenteries of the septa, until the 

 latter are lost at the point of their convergence in the centre 

 of the floor of the visceral cavity. 



The craspedum, under pressure, displays the following 

 elements. (1.) A clear, colourless, highly refractile sar- 

 code, which, under extreme pressure, has a tendency to 

 draw out into strings, and long-tailed drops, like a thick oil 

 on a wetted surface. (2.) Minute scattered granules, very 

 irregular in shape. (3.) Mulberry-like aggregations of 

 granules, of a clear yellow hue, compactly built together, 

 and firm, which have the appearance of being inclosed in a 

 definite cell- wall. These are generally ovate, but are some- 



