ME. P. H. CAEPENTEE ON THE GEATJS ACTINOMETEA. 7 



ill preference to it, paid very little attention to the soft parts of either of the Comatala 

 which he dissected. 



In the following year, however, De Blainville ^ described the visceral mass at some 

 length. Like his predecessors, he adopted Lamarck's genus Comatitla, making it the 

 only representative of his section, " Lcs Asterencrinides libres," Avhile at the same time 

 he acknowledged the prior claims of de Freminville's name Aiitedon. He was, of course, 

 acquainted with Lamarck's error respecting the position of the mouth, which he 

 described as " assez anterieure, isolee, membraneuse, au fond d'une etoile form6e par cinq 

 sillons bifurqvies." The species which he dissected was a foreign one preserved in 

 spirit ; it had a large number of arms ; and from the not very clear description which lie 

 gives of its ventral surface it would seem to have been a true Actinometra. 



After speaking of the tentacular furrows on the ventral surface of the arms, he says ^ 

 " En suivant ces especes de sillons dont le nombre est proportionnel a celui des digitations 

 du rayon, on arrive par tin sillon unique pour chacun d'eux et qui en occupe la base, au 

 centre d'une sorte d'etoile a bords epais, franges, et par suite a la bouche qui est au fond. 

 L'etoile formee par la reunion des sillons des rayons n'est pas symetrique, c'est a dire que 

 ses branches sont tres-inegales : les unes que j'appellerai les anterieures, ctant bien plus 

 courtes que les autres, ou posterieures. II en est resulte que la bouche n'est pas au 

 centre de l'etoile, mais bien plus proche d'un c6t^ que de I'autre : elle est assez difficile a 

 voir au contraire d'un autre orifice, dont il va etre question, et que M. de Lamarck 

 paroit avoir pris pour elle. Elle est profondement enfoncee dans l'etoile des sillons : eUe 

 est ronde, sans aucune armature et conduit immediatement dans I'estomac." 



The above description implies, if I rightly understand it, that the mouth of De Blain- 

 vUle's specimen was nearer to one side of the disk than to the other, so that the primary 

 trunks of the ambulacral grooves were of unequal lengths. This will be subsequently 

 seen (section 14) to be the principal distinctive character of the genus Actinometra. 



De Blainville evidently attached no importance to the position of the mouth as a 

 character of systematic value in the determination of the species of recent Comatiilce ; 

 and from his definition of it as " assez anterieure," it would almost appear as if he 

 supposed the other species to agree in this respect Avith the one dissected by him. 



This is, in fact, the case in five out of the eight species described by Lamarck, with 

 which De Blainville was probably acquainted, and to which he added no new ones, 

 except that he gave the name of Comatula harlxita to Linck's third species oiDecacneiims, 

 the fimhriata of Barrelier, or " barhata "of Linck. Lamarck had been uncertain to which 

 of his species he should refer it, although, as we have seen above (section 1), it is really 

 only a local variety of his C. medUerranea. 



Like the other naturalists of his time (1838), Agassiz ^ also adopted Comatula in preference 

 to the other generic names of this type, but defined it as having the " bouche ccntrale en- 

 foncee," and Avith the five '•' rayons du disque bifurques," thus limiting the number of 

 arms in the genus Comatula to ten only. At the same time he erected Lamarck's sjiecies 

 C multiradiata, Avith sixty or more arms, into a new genus, Comastcr, Avhich he defined as 



Manuel d'Actinologio, (Paris, 1834) p. 249. = Op. clt, p. 251. 



" Prodrome d'uue ilonographio des Eadiaires ou Eeliinodermes," Ann. des Scion. Nat. 2'^ serie, Zool. vii. p. 257- 



