222 J. H. ASHWORTH. 



On examining a transverse section of the upper portion of a stem of 

 the colony, the ccelentera in the peripheral portion of the stem are 

 seen to be smaller than those in the central portion, and some of them 

 are obviously the ccelentera of very young polyps (PI. XX., Fig. 9, 

 right). 



1. The buds arise in connection with that portion of the superficial 

 endodermic canal system situated at the edge of the summit of the stem. 

 When a bud is about to be formed, the superficial canal becomes enlarged 

 and the oviter wall of the canal becomes pushed outwards towards the 

 surface of the stem. This produces a small tubercle upon or immediately 

 under the edge of the expanded end of the stem. The tubercle 

 increases in size, and its distal end soon becomes divided into eight 

 small pouches which become the tentacles of the polyp (PI. XIX., 

 Fig. 4). The divisions between the pouches are the mesenteries of the 

 polyp, and they gradually grow inwards into the ccelenteron. The eight 

 mesenteries are already formed in the young polyp shown in Fig. 4. 



In the centre of the free end of the bud there is a slight depression, 

 and a small darker area which marks the position of the future mouth 

 (Fig. 4 Mo.), and also the ingrowing plug of ectoderm which forms the 

 stomodaeum. Sections of this bud show that the stomodseum is 

 •14 mm. long, and rather flattened laterally. Its oral end is still solid, 

 but the inner portion has become tubular, and its cavity opens into 

 the ccelenteron of the polyp. The distance from the depression indi- 

 cating the position of the mouth to the innermost portion of the ccelen- 

 teron is '4 mm. Mesenteries are distinguishable only in the upper 

 three-fifths of the ccelenteron. In other respects this polyp resembles 

 the one described below, and drawn in Fig. 28. 



2. A slightly older polyp (No. II. in table, p. 215, and drawn in 

 section, Fig. 28), "43 mm. long, possesses tentacles which are not 

 all of the same size. The dorsal and ventral ones are largest 

 (about - 12mm. long), the two lateral ones a little smaller, and the 

 remaining four still smaller. These differences in size are very well 

 seen in transverse sections through the polyp at the level of the mouth. 

 A second specimen of the same size was cut longitudinally, and shows 

 several interesting points (Fig. 28). The stomodseum is about 

 •32 mm. long, and is tubular along the greater part of its length. 

 The mouth is, however, closed partly by approximation of the walls 

 of the stomodseum and partly by a small plug of mucus. The 



