32 NATURAL HISTOR"? OF 



the muscular layer is a deeper zone of the ectoderm 

 which may have nervous functions. This he calls the 

 claviform tissue. The tentacles terminate in capitula 

 in which this claviform tissue is represented by a rod- 

 like tissue, " forming a thick hemispherical cap over 

 the muscular lamella and endoderm of the tentacle, 

 and composed of exceedingly slender prisms closely 

 applied, with their inner ends resting on the muscular 

 lamella, to which the prisms are perpendicular. Ex- 

 tending in a radiating direction from the convex surface 

 of the rod tissue towards the exterior of the tentacle, 

 may be seen numerous fine filaments, each of which, 

 making its way among the cells of the ectoderm, 

 terminates in a very delicate transparent oviform sac, 

 which carries a minute styliform process. Within this 

 sac is an oviform capsule, with firm transparent walls, 

 having immersed in its clear refringent interior a 

 cylindrical cord wound upon itself in two or three coils, 

 which cord may be forced out through the smaller end 

 of the capsule." Prof. Allman "is compelled to regard 

 the whole system as an apparatus of sense, in which 

 sight and touch show themselves in one of their earliest 

 phylogenetic stages, in which they have not yet 

 become fully differentiated from one another." C. F. 

 Jeikeli* also considers that he has discovered sense 

 organs in the tentacles of Eudendrium, confined to the 

 ectoderm, which sense organs appeared to be continued, 

 as a nervous system, into the coenosarc. The palpocils 

 found on the false tentacles of the Pennariidce, and on 

 the tentacles of Clava, &c., appear also to have a 

 sensory action. 



In addition to the alimentary polypites and repro- 

 * Zool. Anzei-. v. (1881), 43, 44. 



