12 ME. P. H. CARPENTER ON THE GENUS ACTINOMETEA. 



weichung allerdings vorhanden, cr liegt ganz zur Seite, cloch ist dies niclit die Ursac h 

 des Unterschiedes, es gibt vielmehr auch Comatulen von der gewblmlichen Anordnung 

 der Purcben, Lei denen gleichwohl der Mund seitlich, die Afterrohre central steht. Pig. 

 von C. multiradiata (PL I. fig. 4). Die fragliche Abweichung beruhrt vielmebr darauf, 

 dass die fiinf Purcben nicbt symnietriscb fur die fiinf Gruppen der Arme vertbeilt 

 werden, sondern dass von den fiinf Purcben einzelne herrschend werden und Aeste an 

 die meisten Arme abgeben. Indein diese Hauptfurcben, nachdem sie die Scbeibe 

 umzogen, sicb wieder annahern, so entstebt der Scbein eines Cirkels. An in Weingeist 

 aufbewahrten Exemplaren siebt man indcss, dass es kein gescblossener Cirkel ist;" and 

 further on (p. 10) be says, " Icb werde daber bei den Arten wo fiinf centripetale Purchen 

 beobachtet sind, den NamenJfec/o in Klammer clem Gattungsnamen Comatula beifiigen, 

 wo aber weniger Purcbcnstiimme den excentrischen Mund erreichen, den Namen Acti- 

 nometra demselben Gattungsnamen Comatula folgen lassen. Also z. B. Comatula 

 (Alecto) europcca; Comatula (Actinometra) Solaris" 



Miiller does not appear to bave been acquainted with De Prcminville's name of An- 

 teclon ; but be distinctly states tliat Leacb's genus Alecto was constituted a year earlier 

 than Lamarck's Comatula. He bad in bis earlier communications employed the two 

 indifferently and as equivalent to one anotber ; but wben be became acquainted with tbe 

 type represented by Comatula Solaris and elevated it into a new genus, or rather sub- 

 genus, Actinometra, in contradistinction to Alecto, be retained Lamarck's name Coma- 

 tula, probably on account of its being so well known, and employed it to designate the 

 genus in which he included the subgenera Alecto, Actinometra, and Comaster. 



Thus the sole cbaracter by which Midler distinguished the first two of tbese subgenera 

 from one anotber was tbe number of groove-trunks reacbing tbe peristome, irrespective of 

 the position of tbe moutb. It is tberefore easy to understand that, as many of the spe- 

 cimens which he examined were dry, and as in otbers, although preserved in spirits, tbe 

 arms were contracted over tbe disk so as completely to conceal it, be was unable satis- 

 factorily to determine more than three species of Actinometra. Two of these, Act. Solaris 

 and Act. Wahlberghii, have been already mentioned; tbe tbird was tbe small Comatula 

 rotalaria of Lamarck. 



(§9) The Aster ias pectinata of Retzius, which presented the same " Bildung des 

 Schcitels ' as Act. Solaris, resembled it so greatly in other respects, that Miiller 

 regarded the two as almost identical, or, at any rate, as presenting only varietal 

 differences 1 . 



lie seems also to have come to the conclusion that the other species described by 

 Betzius, the Asterias multiradiata, Linn., had a prior claim to this specific name over 

 either of the similarly named types described by Goldfuss (Comaster) or Lamarck (Co- 

 matula multiradiata) ; for be described it as " Comatula (Alecto) multiradiata nob." 3 . 

 It is difficult to understand why he called it Alecto; for he had already 3 described this 



1 'Gattung Comatula,' p. 52. - Ibid. p. 25. 



3 Wiegniann's Arehiv, 18-13, i. p. 133, and ' Gattung Comatula,'' pp. 9, 10. 



