290 J. H. ASHWORTH. 



dorsal mesenteries bear mesenterial filaments, and these have 

 a typical course and structure. Owing to imperfect preserva- 

 tion it is impossible to say anything definite about the cells of 

 the other mesenteries, but no ventral or lateral mesenterial 

 filaments are visible. 



The coelentera of the polyps may be traced a considerable 

 distance into the stem, those of the primary polyps being con- 

 tinued down to the base of the colony. In the upper portion 

 of the stem the coelentera contain many ova, each of which is 

 surrounded by an endodermic follicle attached to the mesen- 

 teries. The largest of these ova measure '3 mm. to '4 mm. in 

 diameter. 



Siphonozooids (fig. 39). — Spicules are not so numerous 

 in the ectoderm of the zooids as in that of the polyps. 



The storaodseum is very badly preserved in most of the 

 specimens. A few of the zooids situated near the edge of the 

 summit, however, are rather better preserved, and two of 

 these (S 3 and S 7 in the table, p. 288) have been sectioned and 

 the stomodseum examined. In the zooid 2*3 mm. long the 

 stomodaeum measures '6 mm., and shows a well-marked 

 siphonoglyph, the cells of the lower '2 mm. of which bear 

 flagella. The other specimen (S 7 in table, see also fig. 39) 

 is 5 mm. long. Its stomodaeum measures *8 mm. long, and the 

 cells of the lower '4 mm. of the siphonoglyph bear flagella. 



Thus both autozooids and siphonozooids of this specimen 

 possess a siphonoglyph, the cells of the lower half or third of 

 which bear flagella. This does not agree with the observations 

 of Hickson (1883, p. 696) on a specimen of Heteroxenia, in 

 the siphonozooids of which he found a well-marked siphono- 

 glyph, but in the autozooids a complete absence of siphono- 

 glyph. 



The siphonozooids possess the usual eight mesenteries, but 

 they are extremely thin, and retractor muscles are not visible 

 upon them. The dorsal mesenteries bear mesenterial fila- 

 ments (fig. S9, D.M. F.), which run in a sinuous course down 

 the dorsal side of the polyp, and a short distance into the 

 portion of the ccelenteron contained in the stem. The coelen- 



