Crinoidea. 451 



regions all have loiig arms. This I take to show that these species have 

 attained their present habitat by very easy stages (and very long ago) so 

 that in all their component systems the metabolic processes have at all 

 times maintained the same relative balance. 



It should perhaps be mentioned that the shortening of the arms is 

 noticeable not only in Comatulella Irachiolata, but in all (except possibly 

 in one) of the comatulids from southern Australia regardless of the groups 

 to which they belong. 



The shortening and broadening of the arms in Comatulella brachiolata 

 has produced a curious type of pseudo-biserialism, for the brachials of one 

 side (speaking in reference to the primitive biserial arrangement) often 

 end in a point some distance from the opposite side. This might be sup- 

 posed to be a relic of the primitive biserialisni, but in reality it is a 

 purely secondary condition, due merely to normal growth changes. The 

 brachials of the ten-armed comatulids are wedge-shaped; addition to their 

 outer borders thus lengthens the longer side, at the same time diminishing 

 the shorter, which finally is reduced to a point or apex, after which no 

 further growth is possible, though the longer sides proximal and distal to 

 this point may further increase; such increase results in the lateral pro- 

 duction of these longer sides, which are now in apposition, and the for- 

 mation of a sutural line extending outward from the apex of the intervening 

 brachial at right angles to the longitudinal axis of the arm. 



Genus Comatula Lamarck. 

 Comatnla purpurea (J. 3IUller). 



Literature: See ''The recent Crinoids of Australia". 



Localities: Turtle Island (19 54' S. lat., 118 54' E. long.); 

 VII. 05 (1 specimen). Stat. 14, Sharks Bay, Freycinet Reach, 

 west of Mid die Flat as far as the nor them point ofHeirissou 

 Prong; 11 1C meters; bottom at first sandy, later rock with coral; 



12. IX. (3 specimens). Stat. 15, Sharks Bay, NNE of the nor- 

 thern point of Heirisson Prong; 11 12 Y 2 meters; rocky bottom, 

 with coral; 18. VI. (1 specimen). Stat. 19, Sharks Bay, central 

 channel of Useless Inlet; 7 meters ; rocky bottom, with dead coral ; 



13. IX. (3 specimens). Stat, 21, Sharks Bay, central channel 

 and pearl bank, Useless Inlet [depth and character of bottom not 

 given]; 23./30. VIII. (2 specimens). Stat. 26, Sharks Bay, Sunday 

 Island; 5 J /2 meters; rocky bottom, with coral; 17. VI. (2 specimens). 



V V i c i n i t y of Perth (2 specimens). 



Further Distribution. D u n d a s S t r ait; " n o r t h w e s t e r n A ti s 



29* 



