A MONOGRAPH OP THE EXISTING CRINOIDS 345 



In a paper on the crinoids of the African coasts published in 1911 I described 

 Amphimetra (= Heterometra) africana, and in a memoir on the crinoids of Australia 

 I published a key to the Australian genera in which Amphimetra was separated from 

 Craspedometra and Heterometra by the same character — the very short brachials — 

 used in 1909. The Austrahan species included variipinna (= Heterometra crenulata), 

 milberti (=A. tessellata tessellata), and discoidea (=A. tessellata discoidea). 



In a paper on the crinoids of the Leyden Museum published in 1911 I gave notes 

 on the type specimen of Amphimetra pinniformis, and in a paper on the crinoids of 

 the Paris Museum published in the same year I described the type specimen of M tiller's 

 philiberti under the name of Amphimetra philiberti (under which I placed A. mortenseni 

 as a synonym), gave notes on the type specimen of Comatula jacquinoti, calling it 

 Amphimetra milberti, and recorded a specimen of Amphimetra discoidea. 



In my memoir on the crinoids of the Indian Ocean published in 1912 I differen- 

 tiated Amphimetra from Heterometra on the ground that in the former the middle and 

 distal brachials are excedingly short and discoidal and the elements of the IBr series 

 and lower brachials are swollen, whereas in the latter the middle and distal brachials 

 are more or less obliquely wedge-shaped and not especially short, and the elements 

 of the IBr series and lower brachials are not swollen. I said that the species of Amphi- 

 metra have 10 or more arms, those of Heterometra more than 10 arms. Under Amphi- 

 metra I included philiberti (with Amphimetra mortenseni as a synonym), variipinna, 

 producta, schlegelii, africana, milberti, laevissima, molleri, parilis, discoidea, ensifer, 

 denticulata (Antedon denticulata P. H. Carpenter, 1888), and pinniformis. 



In 1912 Dr. Clemens Hartlaub published a short account of my treatment of the 

 Milberti group but did not comment upon it. In his discussion of the included species 

 he used Carpenter's classification. A specimen of Antedon milberti (= Amphimetra 

 tessellata tessellata) was described and figured. 



In 1913 Dr. August Reichensperger recorded and described specimens of Amphi- 

 metra variipinna, A. discoidea, and A. milberti, and critically discussed the interre- 

 lationships of the last two. 



In a paper on the crinoids of the British Museum published in 1913 I gave notes 

 on specimens of Amphimetra crenulata, A. nematodon, A. anceps, A. producta, A. flora 

 (sp. nov.), A. africana, A. milberti, A. molleri, A. discoidea, A. papuensis (this name 

 here appears for the first time), A. pinniformis, and A. denticulata. 



For some time it had been apparent that Amphimetra was quite untenable on the 

 basis of the characters assigned to it in 1909, 1911, and 1912, and in the sense in which 

 it was used in the report on the crinoids of the British Museum in 1913. No hard and 

 fast line could be drawn between species with exceedingly short and those with longer 

 brachials. Though generally speaking such a division was indicated in the species 

 of Himerometridae with Pi smaller than P 2 and the cirri not smooth and tapering to a 

 point distally, the shape of the brachials varies with age and size, and in some species 

 there is always considerable individual variation. The wholly unsatisfactory nature 

 of the character chiefly relied upon for separating Amphimetra from Heterometra was 

 clearly shown by the inclusion of anceps in Amphimetra and quinduplicava in Hetero- 

 metra in 1909, anceps and quinduplicava subsequently proving synonymous. 



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