I2O 



MANUAL OF ZOOLOGY. 



Eudendrium, a genus of the Corynida, which is not uncommonly found 

 attached to submarine objects, usually in tolerably deep water, may be 

 taken as a good example of the fixed and composite division of the order. 

 The hydrosoma consists of numerous polypites, united by a coenosarc, 

 which is more or less branched, and is defended by a horny tubular poly- 

 pary. The polypites are borne at the ends of the branches and branchlets, 

 and are not contained in " hydrothecae, " the polypary ending abruptly at 

 their bases. The polypites are non-retractile, of a reddish colour, and 

 provided with about twenty tentacles, arranged round the mouth in a 

 single row. Tubularia (fig. 44) is very similar to Eudendrium^ but the 



hydrosoma is either undivided or is 

 very slightly branched. The hydrosoma 

 consists of clustered horny tubes, of a 

 straw colour, and not unlike straws to 

 look at ; hence the common name of 

 pipe- coralline given to this zoophyte. 

 Each tube is filled with a soft, semi- 

 fluid, reddish ccenosarc, and gives exit 

 at its distal extremity to a single poly- 

 pite. The polypites are bright red in 

 colour, and are not retractile within their 

 tubes, the horny polypary extending only 

 to their bases. The polypites are some- 

 what conical in shape, the mouth being 

 placed at the apex of the cone, and they 

 are furnished with two sets of tentacles. 

 One set consists 'of numerous short 

 tentacles placed directly round the 

 mouth ; the other is composed of from 

 thirty to forty tentacles of much greater 

 length, arising from the polypite about 

 its middle or near the base. Near the 

 insertion of these tentacles the genera- 

 tive buds are produced at proper sea- 

 sons. The generative buds remain per- 

 manently attached, but each is furnished 

 with a swimming-bell, in which canals 

 are present. The manubrium is destitute 

 of a mouth, and " the swimming-bell is 

 converted into a nursery in which the 

 embryo passes through the later stages 

 of its development" (Hincks). 



Coryomorpha nutans may be taken 

 to represent those Corynida in which 

 there is no polypary and the hydro- 

 soma is simple. It is about four inches 



in length, and is fixed by filamentous roots to the sand at the bottom of the 

 sea. It consists of a single whitish polypite, striped with pink, and ter- 

 minating upwards in a spear-shaped head, round the thickest part of which 

 is a circlet of from forty to more than one hundred long white tentacles. 

 Above these comes a series of long, branching gonoblastidia, bearing gono- 

 phores, and succeeded by a second shorter set of tentacles which surround 

 the mouth. The gonophores become ultimately detached as free-swim- 

 ming medusoids. 



Another remarkable example of the Corynida is Hydractinia (fig. 45). 

 In this genus the polypites are gregarious, and the polypary forms a horny 



Fig. 44. Corynida. Fragment of 

 Tubularia indivisa, natural size. 



