MR. P. H. CAEPENTEE ON THE GENUS ACTESTOMETEA. 3 



fering very considerably from the type represented by Becacnemiis {Antedon) rosacea, 

 althougli resembling it in only having ten arms. 



In like manner both of Linck's species of his genus Caj)iit-lfeclusce, the one an 

 Antedon and the other an Actinometra, were united by Linnseus, together with a many- 

 armed specimen described by Retzius, into one species, Astenas multiradiata. 



(§3) For some years after the commencement of the present century the Linnean 

 nomenclature held its own, and the few species of recent Comatulse with which the 

 naturalists of that time were acquainted were described as different species of the 

 Linnean genus Asterias. 



The first among the post-Liunean zoologists who recognized the claims of this form of 

 Sea Star to a distinct generic rank was De Freminville ^, who in 1811 presented to the 

 Societe Philomatique de Paris a " Memoire sur un nouveau genre de Zoophytes de 

 rOrdre des Eadiaires," to which he gave the name of Antedon. His definition of the 

 genus was as follows : — " Animal libre, a corps discoide calcaire en dessus, gelatineux 

 en dessous, environne de deux rangees de rayons articul^s, pierreux, perces dans leur 

 largeur d'un trou central; ceux du rang superieur plus courts, simples, et d'egale 

 grosseur dans toute leur longueur ; ceux du rang inferieur plus longs, allant en dimi- 

 nuant de la base a la pointe, et garnis dans toute leiu' longueur d'appendices alternes 

 ^galtment articules; bouche inferieure et centrale." 



It is not very clear which of the two apertures on the ventral (or, as ho called it, 

 inferior) side of the disk was regarded by De PreminviUe as the mouth ; it is very pro- 

 bable that, as he was only able to examine a spirit-specimen, he failed to recognize more 

 than one — that namely, which, placed at the extremity of a long tube projecting from 

 a point near the centre of the disk, we now know to be the anus. 



Adams ^ wlio had studied living specimens of Linck's Decacnemus rosacea, had, how- 

 ever, pointed out some years previously the existence of two orifices to the digestive 

 cavity ; but his observations seem to have escaped notice ; for Lamarck ^ MiUer *, and 

 many other naturalists, all regarded the apertvire at the end of the anal tube either as the 

 mouth alone or as a combined moiith and anus ; and it was not till 1823 that the exist- 

 ence of distinct oral and anal orifices was fully recognized. 



It was announced as a new discovery by Leuckart ^, in a letter to Von Schlotheim ; 

 and he was followed shortly afterwards by Meckel ', Gray "', and Heusinger *. 



' Nouv. Bull. d. Scien. par la Soc. Philomat. torn. ii. p. 349. Paris, 1811. 



* " Description of some Marine Animals found on the Coast of Wales," Trans. Linn. Soc. vol. v. p. 7 (1800). 

 ^ Systume d'Animaux sans Vertubres, 2"' ed. (Paris, 1816), tom. ii. p. 532. 



* A Natural History of the Crinoidca (Bristol, 1821), p. 128. 



* Von Schlotheim, Nachfc. z. Pctrefact. Abth. ii. p. 48 (Gotha, 1823) ; and Leuckart, " Einigcs iibcr AstcriJen 

 Geschleoht ComaUda Lam. iibcrhaupt, und iiber Com. mediterranea insbesonderc," Zcitsch. fiir organ. Physik, iii. 

 p. 385 (1833). 



° " Ueber die Oeffnungen des Speisekanals bei den Comatulen," Meckel's Archiv fiir Physiol. Band iii. p. 470 

 (1823). 



" " Notice on the Digcstiyo Organs of the Genus ComaUda and on the Crinoidea of Miller," Ann. of Philos. n. s. 

 vol. xii. p. 392 (182G). 



* " Bemerk. iiber d. Ycrdauungskanal der Comatulen, Meckel's Archiv" fiir Physiol. 1820, p. 317; and "Anat. Un- 

 tersuch. d. Comatula mediterranea," Zeitsch. fiir organ. Physik, iii. p. 366 (1833). 



1* 



