LAFCEA CALCARATA. 



123 



eter (Fig. 186) ; the chymiferous tubes are narrow ; the tentacles have 

 their greatei^t diameter directly at the circular tube ; they are, how- 

 ever, unequally developed, and vary greatly in character. The large 

 tentacles are very contractile ; near the base they have a swelling 

 which consists of small granular cells, with a spot of dark-violet pig- 

 ment-cells on its lower surface (Fig. 187) ; on the opposite side of this 

 bixlb -we find a spur-like projection (see t, Fig. 187), consistmg of large, 

 transparent, 2)olygonal cells ; from this point the tentacle tapers very 

 gradually, and is also made up of larger cells than the basal swelling ; 



these cells are arranged in two rows, and through them runs a thin 

 tube to the tip of the tentacle ; the lasso cells are numerous, and run 

 in a zigzag manner all over the surface of the large tentacles. When 

 new tentacles are formed in the adult Medusae, it is the spur which is 

 first developed, and afterwards the swelling with the pignicntrcells ; the 

 tentacle has then a triangular appearance, and is turned in the opposite 

 direction from the spur ; from this time it lengthens very rapidly, though 

 many of the tentacles are never fully developed. There are besides 

 long thread-like tentacles, which are not hollow, and are exceedingly 



contractile (o, Fig. 187) ; in adult specimens they are not distributed 

 regularl}-, but in young specimens of a quarter of an inch in diameter, 

 having not more than sixteen large tentacles, and sixteen smaller ones 

 (like the large ones) placed between them, we find on the side of each 

 of these sixteen larger tentacles one of these cirri (Fig. 19-4) ; but as 

 the number of tentacles increases, the cirri are not formed with the 

 same regularity. We find still a third kind of tentacle : club-shaped 



Fig. 18.5. One of tlic ovaries and tlio aetinostome. 

 Fig. 18(). Actinostoine, actiiial view. 



Fig. 187. Magnilieil view of a ])i)i'ti(m of tlie circular tnlu'. ^ one of tlie large tentacles, with 

 spur and pignient-<'(dls ; c, one of tlu^ cirri ; <■, elul)-sliaped ap))cndagc. 



Fig. 188. Actinostome and rudimentary ovaries of young Medusa, seen in profile. 



