Miscellaneous. 471 



and buccal pedicellarise show similar characters, but a simpler 

 structure of the sense-organs. The interior epithelium of the valves, 

 which is characterized by an abundance of long cilia, is covered with 

 sense-ceUs, which, however, do not, as in the above-mentioned cases, 

 collect together to form special sense-organs. While in the pedkeU. 

 gemmiformes a strong nerve-stem runs to each sense-organ, in these 

 a number of ramifying nerves are present, running to the epithe- 

 lium. The nerve-stems consist of very fine threads, upon which 

 are seated bipolar and multipolar ganglion-cells. At the bifurca- 

 tions these are accumulated in great quantities. Even where the 

 nerves consist only of a few fibres, the ganglion-cells may be easily 

 distinguished from the cells of the connective substance, partly by 

 their size and partly by their coloration with the most different 

 fluids. Even the finest nerve-fibres also may be easily recognized 

 among the connective fibres by suitable staining. The latter are 

 stained in a much less degree than the nerve-fibres. 



Those pedicellarise which possess sense-organs, i. e. the gemmiform 

 pedicellarise, are also all furnished with glands, which are seated in 

 the walls of the valves. They discharge their secretion through an 

 aperture situated at the apex of the valve, and indeed above thf 

 calcareous hook, or dorsally. The glandular sacs, of which there are 

 one or two in each valve, are of an oval form, and possess a stronglv 

 developed musculature, serving for the evacuation of the slimy 

 secretion. The minute structure of the epithelium lining the glan- 

 dular sacs presents the most various modifications in the diftereut 

 species, but it would be difiicult to describe these without figures. 



Besides the j^cdic ell. r/emmiformes I have found glands in pedicel- 

 larise which cannot without difficulty be arranged under any of the 

 above-mentioned four groups, e. g. in pediccllariae situated on the 

 buccal membrane in Dorocidaris papillata. 



The function of the different pedicellarise has hitherto *been 

 in dispute without the attainment of any agreement, because the 

 presence of sense-organs and glands, and the minute structure in 

 general, has been quite unknown, and only the calcareous pieces 

 have been described. (The only exceptions to this statement are 

 made by Bladen and Eottinger, who detected and described glands 

 in Spha'recliinus granulans.) 



In the first place, the pedicellarise, whatever their form may be, 

 will function as tactile organs ; this is indicated by the numerous 

 nerve-terminations in both the head and the stem. 



The smallest forms, such as the j^^diceU. trifoUata', undoubtedlv 

 cleanse the test from the smallest particles of sand, Protozoa, and 

 foreign bodies in general, whether these are directlj' upon the sur- 

 face of the test or upon the spines. They will also have the function 

 which A. Agassiz has claimed for all forms of pedicellarise. 



The larger kinds, such as the tridactyle pedicellarise, only rarely 

 serve this purpose — primarily they exist for the purpose of keeping 

 off larger living bodies, such as worms &c., and so act as weapons ; 

 but (as I conclude from the transversely striated musculature found 

 only in them) they also serve for attachment to foreign bodies duriiig 

 movement, as has already been established by Romanes and EwarL. 



