10 ME. P. II. CAEPEXTEll ON THE GENUS ACTINOMETSA. 



he says, " Auf clem letzten Saiilengliedc rulicu fiiiif Bcckenglieder, und auf jedem derselbeii 

 eiu llippcn- ( = second radial) uudeiii Scluilterglied (third or axillary radial), auf welchem. 

 zwei einfache Arme eingelenkt sind," from which it is evident that he was wrongly led 

 to regard the first radials as representing the basals of Comaster and Feiitacrinns. This 

 mistake is hardly a surprising one when we consider the remarkable metamorphosis 

 imdorgone by the embryonic or primitive basals, and their concealed condition in the 

 adult Comatula medilerranea. 



Miiller, who examined a very large number of species of Comatula, never found one in 

 which the basals appeared externally, as described and figured by Goldfuss in Comaster, 

 and remarked ' : — " Daraus gelit hervor, dass die Gegenwart wu-klicher Basalia ohue Zer- 

 legung bei einer Icbenden Comatule, auch dann, weun sic wirklich solche besitzt, schwer 

 zu erkennen sein muss. Die Unterschcidung dcr Comaster und Comatula wu-d daher 

 bei der Ordnuug dcr lebenden Comatulen unpractisch." In fact he appears to have 

 given up the genus Comaster altogether ; for he adds in a note : — " Kiirzlich liabe ich 

 die einzige im Museum zu Bonn befindliche Comatula multiradiata (nicht das von Goldfuss 

 zerlegte Exemplar, wovon ich nichts mehr vorfand) untersucht. Ich habe daran nichts 

 Ton Beckenstiicken erkennen konnen. Die Gattung Comaster ist daher wohl zu un- 

 terdriicken." He seems finally ■ to have thought that it might possibly be identical 

 with the C. Bennetti of the Lcyden Museum. As, however, Comaster has not been seen 

 by any naturalist since the time of Goldfuss, its position must still remain in doubt. 



(§ 8) Up to the time of Miiller no one paid any attention, from a systematic point of 

 view, to the arrangement of the tentacular furrows on the ventral perisome of the disk of 

 Comatula ; but Lamarck and De BlainvHlc had, as we have already seen, examined and 

 described, Avith more or less accuracy, a condition which we now know to differ very 

 considerably from that presented by the Decacnemus of Linck, or the Antedon of De 

 Frcminville. Both these observers seem to have regarded the former condition as the 

 normal one, and as common to all Comattilce. Miiller, who does not seem to have been 

 acquainted with then- descriptions (for he makes no mention of them), took up the subject 

 systematically, and soon discovered that, using the distribution of the tentacular furrows 

 as a basis of classification, he could distinguish two, as he thought, very distinct types 

 of the genus Comatula, which he named Alecto and Actinometra respectively. In his 

 earlier communications ■' on the subject he described the ordiuai-y Comatula and T?enta- 

 crintis as having a central mouth and symmetrically distributed tentacular furrows ; 

 i. e. the five main trunks formed by the union of the furrows of the five groups of arms 

 converge directly towards the centre of the disk, being separated by five " iuterpalmar " 

 areas, one of which, slightly larger than the rest, is occupied by the anal tube, which is 

 therefore excentric in its position (PI. I. fig. 5, An.). 



During his visit to Vienna in 1810 Miiller had an opportunity of examining an un- 



' 'Uebcr die Gattung Comatula, Lam., und ihre Artcn,' Separatabdruck aus den Abhandl. Berlin. Akad. 1849, p. 8. 



= Ibid. p. 29. 



^ " Bau des Pcntacrinus," loc. cit. p. 47, and "Wicgm. Archiv, 1840, i. p. 311. 



