ME. P. II. CAEPENTEE ON THE GENUS ACTLXOMETEA. 3 



fering very considerably from the type represented by Decacnemus (Antedon) rosacea, 

 although resembling it in only having ten arms. 



In like manner both of Linck's species of his genus Cajiut-HIedusa?, the one an 

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

 armed specimen described by Retzius, into one species, Asterias maltiradiata. 



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

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

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

 Linnean genus Asterias. 



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

 Sea Star to a distinct generic rank was De Ereminville \ who in 1811 presented to the 

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

 l'Ordre des lladiaires," to which he gave the name of Antedon. His definition of the 

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

 en dessous, environne de deux ran gees de rayons articules, pierreux, perces dans leur 

 largeur d'un trou central ; ceux du rang supcrieur 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 leur longueur d'appendices alternes 

 egalement articules; bouche inferieure et centrale." 



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

 inferior) side of the disk was regarded by De Freminville 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 3 , who 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 3 , Miller i , and 

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

 mouth alone or as a combined mouth 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 5 , in a letter to Von Schlotheim ; 

 and he was followed shortly afterwards by Meckel 9 , Gray 7 , and Heusinger s . 



1 Nouv. Bull. d. Scien. par la Soc. Philomat. torn. ii. p. 340. Paris, 1811. 



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



3 Systeme dAnimaux sans Verfcebres, 2 me e'd. (Paris, 1816), torn. ii. p. 532. 



4 A Natural History of the Crinoidea (Bristol, 1821), p. 128. 



5 Von Schlotheim, Naeht. z. Petrcfact. ALtli. ii. p. 48 (Gotha, 1S23); and Leuckart, "Einiges iiber Asteriden 

 Gesehlecht Comatula Lam. uberhaupt, und iiber Coi . a insbesondere," Zeitsch. fur organ. Physik, iii. 

 p. 385 (1833). 



6 " Leber die Ocffnungen des Speisekanals bei den Comatulen," Meckel's Archiv fur Physiol. Band iii. p. 470 

 (1823). 



7 " Notice on the Digestive Organs of the Genus Comatula and on the Crinoidea of Miller,'' Ann. of Philos. n. s. 

 vol. xii. p. 392 (1826). 



8 " Bcmerk. iiber d. Verdauungskanal dcr Comatulen, Meckel's Archiv" fur Physiol. 182(5, p. 317; and "Anat. Uu- 

 tersuch. d. Comatula mediterranea," Zeitsch. fur organ. Physik, iii. p. 300 (1S:j3). 



1* 



