GQ A NET OF TENTACLES. 



use is made most clearly manifest. The tentacular 

 filaments are in this case also confined to the oral 

 tube. They are numerous, each forming a little 

 tree, with pinnate branches, bearing no small resem- 

 blance to the flower of feathery branchiae, that ex- 

 pands around the mouth of a Holothuria. These 

 branched tentacula are ordinarily bent down across 

 the mouth of the tube, the longest of them just 

 meeting in the centre; alternating with these are 

 placed others of similar structure, but inferior size ; 

 and the interspaces are occupied by others smaller 

 still, and simply pinnate ; so that when the whole 

 occupy their ordinary transverse position, the small 

 ones fill up the angles of the larger, and the branches 

 of all form a net- work of exquisite tracery, spread 

 across the orifice, through the interstices or meshes of 

 which the current of entering water freely percolates, 

 while they exclude all except the most minute floating 

 atoms of extraneous matter. The accompanying 

 figure, which I have drawn from a fine specimen of 

 Pholas dactylus just obtained from the submerged 

 sandstone at Tor Abbey, and at this moment receiving 

 and ejecting its currents in my glass jar, as placidly 

 as if it were still ensconced in its own quiet hole, will 

 give some idea of the form of this tentacular net, a 

 portion only of which is here given, that the ramifi- 

 cation may be seen with greater clearness. (See Plate 

 II. fig. 7.) 



(P. S.) After a Avhile, these beautiful organs lost 

 their elegance, and shrank up into thick wart-like 

 bodies, merely digitated at their tips, in which, if I 

 had not personally, so to speak, known the individual 



