gg BULLETIN S2, UNITED STATES NATIONAL MUSEUM VOLUME 1 



Dr. Clark remarked that the most interesting biological fact about this comatulid 

 is that it is viviparous, that is to say, the eggs are not shed from the genital pinnules but 

 undergo their development in and on them. He noted that the original specimens from 

 which the species paedophora was described carried on the pinnules pentacrinoid larvae 

 in various stages of growth. They were collected in late summer or early autumn 

 (February and March). The specimens taken in Koombana Bay in late spring have 

 the genital pinnules with large eggs and young embryos, not yet pentacrmoids. Each 

 pinnule seems to have 4 or 5 eggs, but usually if development is well under way there 

 are but 3 or 2 embryos. Dr. Clark suspected that only one pentacrinoid develops on 

 each pinnule, the other eggs and embrj'os serving as nourishment. 



lie said he had little doubt but that the whole life history could be easily worked 

 out at Bunbury during a summer and would be a very interesting and valuable study. 

 He also suggested that the work might be done at Fremantle, since this species occurs 

 at Garden Island. 



Dr. Clark said that in alcohol this species undergoes practically no change of 

 appearance, but dried specimens are paler and more rigid. The color of the oral surface 

 is always brown, usually very dark, the disk being marked more or less with whitish. 

 The dorsal side of the arms and cal}^^ is brown, ranging from a distinctly yellowish to 

 a deep somewhat purplish shade. The cu-ri are often purplish, brownish, or even 

 reddish, but are generally very light and often almost white, in rather marked contrast 

 to the arms, which they sometimes nearly equal in length, or even exceed. 



He noted that the cirri are efficient "holdfasts," admirably adapted to the bottom 

 on which the comatulids were living, for this was covered, more or less, with algae 

 (chiefly Cystophora) and other vegetation (chiefly Cymodocea). The dredge came up 

 full of these plants and the various comatulids (not to mention other echinoderms) were 

 well tangled with them and with each other by means of the long recurving cirri. 



Dr. Clark said it is worthy of note that he did not find Ptilometra at Bunbury, or 

 at any other point on the Australian coast. 



Eemarks.— At the time he recorded the three specimens collected by the Hamburg 

 Southwest Australian E.xpedition at Koombana Bay (1911), the author remarked that 

 they had given him considerable trouble. He said that they appear to be exactly com- 

 parable to the Antedon wilsoni described by Bell, and to the Himerometra paedophora 

 described bj' H. L. Clark, both of which proved subsequently to be but the young of 

 species of Ptilometra, the former of P. macronema and the latter of P. mulleri. 



The author wTote that the essential features presented by these little animals are 

 as follows: The coefficient of variability between the three specimens is very high, 

 indicating immatm-e forms with a quite difTcrcnt adult stage. P, is more or less pris- 

 matic, showing that the animal belongs to the Oligophreata. In that group it comes 

 nearest to P, in Ptilometra, with which it agrees in all particulars, even though the 

 pinnules following are smaller instead of larger. The cirri are evidently immature; 

 their distal taper, great length, and large number of segments, as well as the proportions 

 of the segments, agree with the conditions found in Ptilometra macronema, though they 

 are white, and in Ptilometra macronema tlie cu-ri are the darkest part of the animal. 

 The outer pinnules have comparatively short segments, a condition which shows that 

 the animals cannot belong to any group but the Charitometridae, Calometridae, or 

 Thalassometridae (in a broad sense) and, except for the lack of carination and the 

 juvenile characters, they come nearest to the pinnules of Ptilometra macronema. 



