Development of Holothuria Floridana Pourtales 217 



larval holothurid gradually pushes away the remnants of the old 

 egg-shell and begins to creep about by means of the suckers terminat- 

 ing the four primary tentacles first developed, and the one posterior 

 mid-ventral pedicel. It will fix itself by the pedicel and extend the 

 tentacles in hydra-like attitude (PL II, Fig. 7). Now it will turn 

 onto the tentacles with the released pedicel waving aloft, and again 

 it will creep about by means of all of its appendages, assuming curi- 

 ous elephantine postures. Securing food by the suckers, the holo- 

 thurid bends the tentacles until the ends reach the mouth, when 

 the food is pushed into the pharynx. The outer lip of the peristome 

 embraces the proximal halves of the tentacles, forming a web between 

 them which is drawn out when the tentacles are extended. 



During the fourth, fifth and sixth days, the fifth primary tentacle 

 remains as a bud from the mid-ventral radial canal to the left. By 

 the seventh day the bud has appeared externally as a small tentacle 

 and with the exception of an occasional precocious individual it is 

 not until after the seventh day that the fifth primary tentacle devel- 

 ops to the size of the first four (PI. II, Fig. 7, MVll). The lip 

 of the peristome persists as a collar around the bases of the tentacles. 



In the scheme for the adult symmetry of the twenty tentacles 

 (Diagram 1), the origin of the thirteen shown in my series is in- 

 dicated. Each of the first four of the primary tentacles, so Avell 

 inaugurated in the fourth day, is marked A, and the fifth, budding 

 in the fourth day, A5. Following this scheme of symmetry. Table I 

 present the details in the development of the tentacles from the 

 sixth to the eighty-seventh days. After the seventh tentacle, the order 

 of appearance sometimes varies, but the serial numbers, given in 

 DiagTam 1, follow the usual ontogeny. 



By the fortieth day, the sixth tentacle, small but developed (PL 

 II, Fig. 10, KVd2) is clearly seen in the living holothurid. It 

 has evaginated from tho tentacular canal of the primary tentacle 

 dorsad from the right ventral radial canal just after it leaves the 

 radial canal (Diagram 1, E. 6). One specimen of this age has also 

 the bud of the seventh tentacle from the canal of the primary ten- 

 tacle dorsad from the left ventral radial canal (L 7). The day when 

 the bud of the sixth tentacle may have first appeared, I was not 



