The Crinoids feom Dr. S. Bock's Expedition to Japan 1914. 9 



at a certain place is approximately known and evolution-series are 

 brought home, the prospects of identifying young forms are consi- 

 derably brighter. I therefore considered it of a certain interest to make 

 a combination of the young Comasterid forms from the Bonin Islands 

 and, partly by comparing them with one another, partly by studying 

 given evolution-series, try to produce the characteres that might be 

 of systematical value. Thus, among other things, I think I have found 

 that the appearance of the disk can give certain fixed points for jud- 

 ging the systematic position of the young Comasterids. 



The family Zygometridce is represented by 5 forms including one 

 new species and two new varieties. As always, here too 1 have been 

 very cautious in establishing new species and have preferred to set 

 up a new form as a variety rather than as a species if the disting- 

 uishing characteristics have seemed to me to be less decided or I have 

 otherwise had any doubt about the value of the distinguishing marks 

 quoted. Therefore it is very possible that some of the new forms des- 

 cribed as varieties will in future turn out to be new species. 



Of the families Mariametridœ, Colohometridœ, Tropiometridœ and 

 Calometridœ there are, except Cyllometra pulchella n. sp., only previously 

 known species with a number of species J, 5, 2 and 2 respective- 

 ly. Cyllometra disciformis is swept from greater depths than were 

 previously known and because of this the cirrals are exceptionally 

 short in correspondence with A, H. Clarks statement on the Siboga 

 material. Antedon macrodiscus, described by the Japanese Hara 1895, 

 I have put as a variety under Tropiornetra afra, from which it only 

 differs by having a greater number of cirrals. a character that in this 

 case I cannot consider to have a species-distinguishing value, as it is 

 the only differing one. The relation between the genera Galometra and 

 Neometra I have discussed in connection with the description of spe- 

 cimens of Neometra multicolor. 



The family Thalassometridœ appears with -1 species, one of which 

 is new, Stenovielra dentuta, in a certain way intermediate between the 

 genera Stenomeira and Daidalometra. Of Asterometra anthus I have had 

 an opportunity to study a very rich material, which has been subjected 

 to statistical investigation. This has given the result that both the 

 Clarkian species A. acerba and A. lepida cannot be considered as forms 

 differing from the above-mentioned species but might become absorbed 



Nova Acta Reg. Soc. Sc. Ups., Ser. 4, Vol. 5. N:o 6. Impr. ^/« 1922. 2 



