218 ANATOMY OF SPECIAL FORMS. 



into five sliort cylindrical processes, each of which carries on its extremity two or three small 

 globular clusters of thread-cells. 



At the proximal extremity of the manubrium its cavity is prolonged into five small narrow 

 pouches, which are seen at the angles of a pentangular area, which forms its fundus and which is 

 visible when we look down upon the medusa from its vertex (fig. 7). When the manubrium is 

 viewed laterally the pouches give to it the appearance of being suspended by five short roots from 

 the summit of the bell. It is in these pouches that the radiating canals originate. Sometimes 

 one or more of the pouches give off directly two canals ; sometimes a single canal arises directly 

 from a pouch. After a longer or shorter course the single canals will bifurcate, and as the ultimate 

 result ten radiating canals are formed. These pass down at exactly equal distances from one 

 another to the circular canal, into which they open after presenting just before their junction with 

 this canal a marked enlargement of their cahbre. 



All the other authors who have described the Cladonema-mednsn give eight as the number 

 of the radiating canals and marginal tentacles. It is evident that there is in this respect a 

 variation which must not be regarded as pointing to a specific distinction. 



The marginal tentacles correspond in number with the radiating canals, of which they are, 

 in fact, the direct continuation; in my specimens there were therefore ten of them. They are at 

 first very thick, continuing so for some distance from their origin, but as soon as they begin to 

 give off their branches they rapidly taper away to their extremities. A bulbous dilatation with a 

 very distinct ocellus exists at their junction with the circular canal. After continuing simple for 

 about a third of their length they begin to emit peculiar appendages. These are given off 

 alternately, and all direct themselves inwardly or towards the axis of the medusa. The first 

 three of these appendages are veiy different from the others. They are nearly cylindrical, though 

 tapering slightly towards their distal extremity, where each terminates in a spherical capitulum 

 thickly set with thread-cells (fig. 5). Their endoderm is composed of large cells, which give 

 them an irregularly septate appearance, while a line of coloured granules occupies their axis. The 

 proximal one is shorter than the other two, which are equal to one another in length. 



The rest of the appendages consist of very e.xtensile offsets from the tentacle, the last 

 forming a bifurcation with the terminal portion of the tentacle. When extended (figs. 3, 4, 6) 

 they are in the form of cylindrical filaments, all thickly set with spherical clusters of thread-cells, 

 which give them a nodulated appearance, a single cluster, larger than the others, terminating 

 each appendage. When contracted (fig. .5) they are in the form of short, thick, club-shaped 

 offsets. Each tentacle carries four such appendages. 



The tentacle from the point at which the nodulated appendages begin to be given off to its 

 extremity is covered in a similar way with knot-like clusters of thread-cells, and, like the 

 ai)pendages themselves, is terminated by a large spherical cluster. 



The axis of the tentacle presents throughout a continuous tube, which extends laterally into 

 the nodulated appendages as far as their ends, and contains abundance of dark crimson-brown 

 granules, thus contrasting with the smooth capitate appendages, which merely present a few 

 scattered coloured granules in the axis of their large-celled endoderm. At the spot where the 

 last-mentioned appendages are given off the main tube of the tentacle slightly widens, and then 

 again becomes diminished in diameter, to taper away with the tapering tentacle to its distal 

 extremity. 



The three smooth appendages which are given off near the base of the tentacle possess very 



