486 



RECORD OF SCIENCE FOR 1886. 



of the tube is then not a heart, but the site of the production of elements, 

 some of which, becoming free, form the corpuscles of the general cavity. 

 The canaliciili of the madreporite are due to nothing more than the 

 folding of the walls of the vibratile infundibulum, by which the hydro- 

 phoral tube opens to the exterior. Prof. Perrier is convinced that the 

 tube communicates at the point where it unites with the apex of the 

 funnel with the cavity of the sacciform canal. If the canaliculi of the 

 madreporic i)late only lead into the hydrophoral tube or its upper ex- 

 pansion, the tube itself opens into the sacciform canal laterally, and 

 sea water can thus i)ass into the lacunar spaces, which Hamann con- 

 aiders as a schizocoel, into the subambulacral cavities, and into the 

 general cavity." 



Professor Perrier concludes that in star-fishes, "as in echinids and 

 comatulids, sea water plays an important physiological part, but 

 its course is not regulated by as complicated a system of irrigating 

 canals ; from this it is deduced that the echinoderms are divisible into 

 two great groups. One of these contains cystoidea, blastoidea, stelle- 

 ridse, and ophiurida, and the other crinoids, echinoids, and holo- 

 thurians, and it is added that in this phylum, as in ccelenterata and 

 sponges, the penetration of water is a general phenomenon, while it is 

 rare in worms, arthropods, mollusks, and vertebrates. It is therefore 

 concluded that the old division of De Blainville, with certain modifica- 

 tions, may be retained, and that all animals may be divided into three 

 great groups, Protozoa, Phytozoa, and Artizoa." (Comptes Eeudus 

 Acad. Sc, cii, pp. 1146-1148 ; J. P. M. S. (2), vi, pp. G24, 625.) 



WORMS. 



General. 



Resemblances and differences of the nervous system of wortns. — In con- 

 nection with the observations on the development of the uemertean 

 worm named Monopora invipora, Prof. W. Salensky has considered the 

 homologies of certain parts, and especially of the nervous system and 

 proboscis of the nemertean, rhabdoccelous, and aunelidan worms, and 

 gives his views in a tabnlated form, contrasting the various groups. 



The nervous system of the uemertines is contrasted with that of 

 the annelids in one table : 



