iv PHYLUM CCELENTERATA 185 



shapeless lumps stuck over with stones, and thus easily escape 

 observation. Any of the numerous species will serve as an 

 example of the group : the form specially selected is the " Dahlia 

 Wartlet " (Tealia crassicornis), one of the commonest British 

 species. 



External Characters. Tealia (Fig. 138, A) has the form of a 

 cylinder, the diameter of which slightly exceeds its height. It is 

 often as much as 3 inches (8 cm.) across, is of a green or red colour, 

 and habitually covers itself with bits of shell, small stones, &c. It 

 is attached to a rock or other support by a broad sole-like base, 

 sharply separated from an upright cylindrical wall or column, the 

 surface of which is beset with rows of adhesive warts or tubercles : 

 at its upper or distal end the column passes into a horizontal plate, 

 the disc or peristome. In the middle of the disc, and slightly 

 elevated above its surface, is an elongated slit-like aperture, the 

 mouth (mth.), from which streaks of colour radiate outwards. 

 Springing from the disc and encircling the mouth are numerous 

 short conical tentacles (t.), which appear at first sight to be 

 arranged irregularly, but are actually disposed in five circlets, of 

 which the innermost contains five, the next five, the third ten, 

 the fourth twenty, and the fifth or outermost forty, making a total 

 of eighty. 



Obviously the Sea-anemone is a polype, formed on the same 

 general lines as a Hydra or a scyphula, but differing from them in 

 having numerous tentacles arranged in multiples of five, and in 

 the absence of a hypostome, the mouth being nearly flush with the 

 surface of the disc. Its great size and bulk, and the comparative 

 firmness of its substance, are also striking points of difference 

 between Tealia and the polypes belonging to the classes Hydrozoa 

 and Scyphozoa. 



Enteric System. Still more fundamental differences are found 

 when we come to consider the internal structure. The mouth does 

 not lead at once into a spacious undivided enteric cavity, but into 

 a short tube (gul.), having the form of a flattened cylinder, which 

 hangs downwards into the interior of the body, and terminates in 

 a free edge, produced at each end of the long diameter into a 

 descending lobe or lappet (lp.). This tube is the gullet or stomodceum, 

 a structure we have already met with in the Scyphozoa, but which 

 here attains a far greater size and importance. Its inner surface is 

 marked with two longitudinal grooves (A and B, sgph.), placed one 

 at each end of the long diameter, and therefore corresponding with 

 the lappets : they are known as the gullet-grooves or siphonoglyphes. 



The gullet does not simply hang freely in the enteric cavity, 

 but is connected with the body-wall by a number of radiating 

 partitions, the complete or primary mesenteries (mes. 1) : between 

 these are incomplete secondary mesenteries (mes. 2), which extend 

 only part of the way from the body-wall to the gullet, and 



