709 



THE RECENT CRINOIDS OP AUSTRALIA — CLARK. 4^^ 



out some vex'y remarkable facts, but can scarcely be said to have 

 done more; Reichensperger's investigation of the glands and their 

 secretions have opened up interesting questions of physiology. 



The work of Wyville Thomson, W. B. Carpenter, Perrier, and 

 especially of Barrois, Bury, and Seeliger has laid a foundation, 

 though one with many weak spots, upon which to build up the 

 study of tbe compaiative embryology of the Ciinoids ; but no one 

 up to this time has attempted any embryological investigation 

 outside of the genus Antedon, Thomson, Carpenter, and Perrier 

 treating of Antedon bifida, Barrois and Bury of A. inedlterranea, 

 and kSeeliger of A. adriatica. Great results from this study are 

 assured in Australia wliere the genus Antedon does not occur, it 

 being here replaced by many other genera, some of them much 

 more favourable for study in the young stages, and others about 

 whose development nothing whatever is known. 



The composition of the Crinoid skeleton offers an interesting 

 field for investigation. An analysis of the pinnulate arms of a 

 specimen of Metacrimts rotundus from Japan showed 11% of 

 MgCO^. Fearing from the very high percentage of MgCOg that 

 some mistake might have been made in the analysis, I had 

 analyses made of another specimen of Metacrinus I'otnndus from 

 Japan, and of a specimen of Heliometra maxima from very cold 

 water in the Sea of Okhotsk ; the former showed 10-29 % of 

 MgCOg, and the latter 7 %. 



It has been noticed that the littoral Crinoids ar6 more or less 

 limited in their distribution to coast lines well supplied with 

 fresh water, either from rain or shallow rivers ; a careful statistical 

 study of the effect of river water and I'ain water, especially the 

 toxic effect of the dissolved oxygen in the latter, upon the small 

 organisms which serve as Crinoid food, as well as a detailed study 

 of the comparative growth of the Crinoids in areas exposed to 

 and protected from rain, would be certain to yield results of great 

 value. Not only on this point but on all others has the general 

 natural history of the Crinoids been sadly neglected. We are 

 ignorant of the limitations of their chemical, physical, and 

 biological environment and of its influence on their size, colourj 

 development, and local distribution ; no detailed analyses have 

 been made of the stomach contents; we do not know whether 

 they select their food, whether each species eats the same things, 

 or whether the food is uniform or varied or its supply intermittent 

 or constant. The Comasterids have many-coiled intestines whereby 

 we infer they ingest a large proportion of indigestible inorganic 

 matter along with tlieir food, though we do not know anything 

 about it. Since the numerous coils are not found until late in 

 post-pentacrinoid life, we assume that when young their habits 

 resemble those of the endocyclic forms, but here again we have 

 only a theoretical basis for our belief. 



