202 



COELENTERATA. 



in the funnel-plane (cf. Fig. 158); i.e., the stomach-axis of the body 

 is very long, and the funnel-axis very short. Further, the sub- 

 tentacular ribs (r\ ? A , r 5 , r 8 ) are very short, and reduced to a few 

 plates at the aboral pole, while the sub-stomachal ribs (r 2 , r 3 , r 6 , r 7 ) 

 extend close together along the whole length of each side of the 

 aboral surface of the body. 



The perradial vessels are absent, as the four interradial vessels 

 arise directly from the funnel (in correspondence with the compression 

 of the body). The sub-stomachal meridional vessels run horizontally 

 beneath the long ribs to the ends of the body, while the sub-tentacular 

 (ff l t # 4 5 /7 5 j y 8 ) P ass along the middle of each side of the body, also 

 to the extremity, where they are connected with the sub-stomachal 

 vessels (# 2 ), and with the paragastric vessels which are continued 

 along the flattened oral surface of the body. In the Cestidae generative 

 cells are only produced in the sub-stomachal meridional vessels. 



The tentacular apparatus is hidden in a sheath. There is no 

 projecting tentacle, but a very large tentacle base which is in 

 the sheath. Each tentacle-sheath is continued right and left as 

 a furrow, which extends along its own side of the oral edge of 

 the body to the extremity. The numerous lateral fibres which arise 

 from the tentacle base lie in these tentacular furrows and hang down 

 from them all along like a fringe (Fig. 160), being held in the 

 tentacular furrows by hooks. 



In the Lobatae the body is compressed in the same way, but not 

 to the same extent as in the Cestidae, i.e. the funnel axis is shortened. 

 There are two large buccal lobes, one on each side of the mouth in 

 the stomach-plane. The sub-tentacular ribs are shorter than the sub- 

 stomachal, and at their oral ends arise the four auricles. The auricles 

 are processes of the body, and each carries one row of vibratile plates. 

 The sense-organ lies in a deep pit at the aboral pole, and the ciliated 

 furrows (the so-called nerves), which pass from it, extend all along 

 the ribs. The interradial vessels arise directly from the funnel, and 

 the sub-tentacular vessels anastomose with the paragastric vessels at 

 the base of the auricle. From the point of junction there arises a 

 vessel which forms a loop in the lobes and anastomoses with its fellow 

 of the neighbouring quadrant. The sub-stomachal vessels also form 

 loops and anastomose in the oral lobes. 



The Beroidae are without any tentacular apparatus in both larvae 

 and adults. The body is compressed in the funnel-plane, and the 

 main axis is elongated. The mouth and stomach are enormous, and 

 the lower third of the stomach-wall is closely beset with sabre-like 



