LUCERNARIiE A N D T II E I R A L L I E S. 23 



both as organs of prehension and adhesion, since they are covered on one of the 

 opposite flattened sides with nrticating organs and vibratile cilia, and on the other 

 with adherent vesicles (see § 15). Witli snch an array of grappling apparatns, 

 crowded abont the post-buccal cavity, and with the fact in view tluit these bodies 

 are seen to project ont of the month at times, there cannot be much doubt that 

 they are eminently efficient in capturing and drawing the prey within the folds of 

 the body, and into the general cavity. 



53. The posterior division (^l^) of the main cavity lies altogether behind the 

 entrance to the four lateral compartments, and is embraced within the broad 

 conical termination of the umbella. Its outlines correspond almost exactly with 

 the exterior configuration of the wall which contains it. Anteriorly it is directly 

 continuous with the buccal cavity, and diverges in four different directions, right 

 and left, and with very wide passages, into the four umbellar compartments 

 (Jig. 37, t|-')- Pcfsteriorly it is rounded off, and opens (figs. 37, 50, t*) directly and 

 abruptly into the four, circumaxial, longitudinal channels (t'') of the peduncle. At 

 four equidistant points in its lateral periphery there are as many longitudinal low 

 ridges, which trend in a direct line from each of the partitions of the umbella 

 backward, and gradually thin out and disappear a sliort distance in front of the 

 apertures of the canals of the pedicel. They are composed, in the main, of fibres 

 (r), which may be traced, anteriorly, into the flabelliform muscles which constitute 

 a part of, and lie on each side of, the partitions, and posteriorly they plunge into 

 the solid mass of the peduncle and run (/•) to its extreme posterior end, keeping 

 strictly in the middle of the spaces which intervene between the longitudinal 

 canals (t^), 



§ 9. The Peduncle. {VI i, .%. 17; V\. u,figs. IS, 19; Tl. ui,fig. 37; PI. iv,/</s. 

 47% 50, 51 ; ri. y,Ji</. 52; PI. \i,jig. 66 t-t''.) 



54. The peduncle is unquestionably the preeminent feature of interest in con- 

 sidering the morphological relationships of this peculiar order. It is that which, 

 added to the umbellar division of the body, caps the climax of the process which 

 is at work reducing the difi'use medusoid and hydroid cephalisms of the lower 

 groups to more intimate alliances in the higher families, and finally combining them 

 in a single unit of form, the hydra-medusa individuujn, Lucernariu. The com- 

 plicated organization of the peduncle — the hydra clement of our coenotype — sur- 

 passes that of any hydra (scyphostoma included) thus far met with. The mode of 

 junction with the umbella has already (46) been described in reference to the latter. 

 The precise point is not observable on the outside, but the transparency of tlie wall 

 allows the interior to be seen with full clearness, and in fact the organs there are 

 so conspicuous as to blend in the vision of the exterior. By this we learn that the 

 apertures (t^ of the peduncular canals (r') are on a line with the spot where the 

 posterior, conical termination of the umbella fades into the cylindrical shaft of 

 the peduncle. From this point the caudal subdivision of the body retains its cir- 

 cular form in general outline, but is subdivided lengthwise by four furrows (Jigs. 

 52, 66 r'^), which extend to the posterior truncate termination, and even over the 



