230 J. H. ASHWORTH. 



more clearly seen. Note also that the polyps are smaller and closer together 

 near the edge than nearer the middle of the summit. The stem immediately 

 to the right of this also shows that the young and small polyps are on the 

 edge, while the large polyps are near the middle of the summit. The colour 

 of the drawing is, as nearly as possible, the colour of the specimen in spirit. 

 x3. 



Plate XIX. 



Fig. 2. — View of the polyp XXI. in the table, p. 215. This is one of the 

 largest polyps of the colony. The tentacles show from the outer aspect a 

 single row of pinnules on each side, but from the inner aspect three rows on 

 each side. Note that at the tip of the tentacles the pinnules are not arranged 

 in pairs, x 12. 



Fig. 3. — Views of the tentacle of a large polyp. A and B are views of the 

 tip, C and D of the base of a tentacle. A and O show the outer or aboral side, 

 B and D the inner or oral side. The narrow area free from pinnules, which 

 extends along the middle line of the oral face of the tentacle, is well seen in D. 

 At the tip of the tentacle, B, the pinnules are in rwo rows only on each side of 

 the middle line, x 24. 



Fig. 4. — Lateral view of the youngest polyp ('32 mm. long) in the colony (I. 

 in table), x 40. 



Fig. 4a. — Oral view of the same polyp. The tentacles are eight rounded 

 lobes. The depression (Mo.) in the centre of the oral disc indicates the position 

 of the future mouth, and the darker area below it is the ingrowing plug of 

 ectoderm which forms the stomodasum. x 40. 



Fig. 5. — An older polp - 95 mm. long (V. in table). The tentacles are trilobed 

 at the end, i.e., the first pinnules are being formed, x 24. 



Fig. 6.— A polyp 1"42 mm. long (VIII. in table), x 24. 



Fig. 6a. — View of the oral face of a tentacle of the polyp shown in Fig. 6. 

 Two rows of pinnules on each side of the middle line are now present. X 24. 



Fig. 7.— A polyp 2-27 mm. long (XII. in table). X 24. 



Fig. 7a. — View of the oral face of a tentacle of the polyp shown in Fig. 7. 

 In the middle part of the tentacle, three rows of pinnules on each side of the 

 middle line are now distinguishable. X 24. 



Plate XX. 



jr IG . 8— A thick longitudinal section through the upper part of one of the 

 stems. The section passes along the dorso- ventral axis of a young polyp (VI. 

 in table, p. 215)growing out just under the arched summit of the stem. On 

 the dorsal or upper side of the polyp one of the dorsal mesenteries (D.M.) is 

 cut through obliquely for a short distance. The stomodajum [St. ), siphonoglypb 

 (-Si.), the course of the dorsal mesenterial filaments (D.M.F.), the thin edge 

 of the ventral mesentery (V.M.), and the connection of the ccelenteron with 

 the canal system are shown. Three ccelentera of older polyps are also shown. 



