ro8 



'•THKTIS" SCIKNTIFIC KESULTS. 



sublittoral species cannot cross as their hirvse develop the normal 

 impulse for fixation in a shorter time than that required to drift 

 to the other side, and thus fall into deep water amidst a cold and 

 unnatural environment, and perish. Riveis of considerable 

 volume and depth act in exactly the same way ; the larvfe, on 

 account of their short duration of existence as larvee, cannot pass 

 around the fatal fresh water, nor, if the river be very deep, can 

 they pass beneath it. 



(3). The Crinoids are the most highly calcified of organisms, 

 and the most uniformly calcified as a class, exhibiting, so far as 

 we know, but very slight variation. The smallest Comatulids, 

 with arms scarcely half an inch long, probably never have less 

 than 20,000 distinct skeletal elements, while it has been estimated 

 that the large Pentacrinites possess 5,000,000 ; personally I think 

 the latter estimate slightly too conservative as it takes no account 

 of the visceral skeleton. Thus, the Crinoids are peculiarly suscep- 

 tible of preservation, and hence their excellent palseontological 

 record, surpassing even that of the molluscs. 



As subjects for study in all lines the Crinoids offer wonderful 

 possibilities, and in no place can their study be prosecuted to 

 such advantage as in Australia where the multitude of forms 

 easily available occur largely within easy reach of important 

 scientific centres. It is mainly to Australia, therefore, that the 

 world must look for the solution of the problems dealing with 

 these animals, and the Australian naturalists will be the ones to 

 whom the naturalists of other lands must look for guidance. 



Only a very feeble beginning has been made in the study of 

 the recent Crinoids, even from a systematic standpoint. The 

 proportion of known to unknown forms is still verj small, as is 

 graphically brought out by the study of any large collection, and 

 remarkable new genera are being brought to light with increasing 

 frequency. 



The anatomy of two species of Antedon, A. bifida and A, 

 inediterranea, has been studied by Ludwig, Perrier, Hamann, 

 and the two Carpenters, who also discussed in more or less detail 

 that of Heliometra glacialis and a few other species such as 

 Comanthus parvicirra, Neocomatella alata, and Comatella nigra ; 

 but the refinement of teclmique and especially of methods of 

 fixation .since their work was done— work which was almost 

 wholly based upon more or less poorly preserved alcoholic material 

 — have made the field one of very great promise, entirely 

 untouched so far as Australian species are concerned. 



Dendy's studies on the regeneration of the disk, and Minckert's, 

 Perrier's, and Przibram's on the regeneration of the disk and 

 arms have indicated most interesting lines of work, and pointed 



