I 



DEVELOPMENT OP ANTEDON (COMATULA, LAMK.) EOSACEUS. 681 



memoirs of Guettard and Ellis on the recent Pentacrinus ; nor was it corrected in the 

 edition of the same work subsequently published (1788-1793) by Gmelin, — By Blu- 

 MENBACH ', however, the Ckixoidea were conectly placed, in proximity with the recent 

 Pentacnmis of Guettard, in his division Vermes Crustacea, with which in his later 

 editions he associates the name Echinodermata'' as a synonym ; but he does not in any 

 way recognize Antedon as a distinct type having a special relation to the Crinoids. 



Our Antedon rosacem was described and figured by Pexnant in his 'British Zoology*,' 

 under the Linnean names Asterirts bifida and Astcrias decacnemos ; and though no new 

 light was thrown by him either on the peculiarities of its structure or on its affinities, 

 yet it is deserving of notice that he specially alludes to the ventral as well as the dorsal 

 surface being furnished with short simple rays, which are well represented in his figure. 

 These "ventral rays," as Lamarck afterwards pointed out, are in reality the basal pinnules 

 of the arms, which are much longer than the rest, and (as I shall show hereafter) 

 differ from them very remarkably in structure ; but the manner in which they arch over 

 the ventral surface of the central disk is such as to suggest to a superficial observer an 

 analogy to the "short simple rays" or rather "cirrhi" of the dorsal surface. — The 

 Antedon rosaceus was again described imder the name of Asterias pectinata by Adams*, 

 another British zoologist of the latter part of the last century; and his notice of it, 

 though very slight, has this remarkable merit, — that it mentions the existence of two 

 orifices to the digestive cavity. " The body," he says, " is covered on the upper side by 

 five unequal valves." [By this expression he seems to indicate the dirision of the ventral 

 surface of the disk into five sectors by the radial furrows converging from the bases of 

 the arms.] "It is remarkable of this species that it is furnished with two apertures, 

 one at the confluence of the valves, the other in the largest valve ; their position with 

 respect to the centre is variable ; the last may readily escape observation, except when 

 the animal chooses to elevate it above the plane of the valve." This observation seems 

 to have been completely overlooked by those who subsequently described Antedon ; its 

 possession of distinct oral and anal orifices having been announced as a new discovery 

 by Meckel in 1823. 



The Class Echinodermata was adopted by Cctvier in his first systematic arrangement 

 of the Animal Kingdom' ; but this neither contains any recognition of the peculiarities 

 of Antedon, nor makes any mention whatever of the Crinoidea. Of tlie ignorance which 

 still prevailed in regard to the real nature of the last-named group, we have a remarkable 



' Handbucli der Naturgeschichtc. Gottingen, 1780. 



' The term Echinodebmata seems first to have been introduced by Klein in his ' Naturalis Dispositio Echino- 

 dermatum' published at Dantzig in 1734 ; but it was limited by him to the EcJiini and their allies, now con- 

 stituting the family Eclnnida, !Not having been able to obtain a sight of the original edition of the ' Handbuch 

 der Naturgeschichte ' of Blcieenbach, I am unable to ascertain whether the- term was applied by him to include 

 the Asieriada and Uolothurkla before it was so applied by Beugibke in the ' Encyclopedic Me'thodique.' in 1792. 



' Edition of 1776-77, vol. iv. pp. 05, CO, tab. xxxiii. fig. 71. \ 



* Linnean Transactions, vol. v. p. 10. ' 



• Tableau ^lementairc do I'llistoire Naturelle des Animaux. Paris, 1797. 



5a2 



