692 DE. W. B. CAEPEiN'TER OX THE STRLX'TUEE, PHYSIOLOGY, AND 



specimen of Pentacrinus Caput-Medusce transmitted by him from Guadaloupe. " La 

 bouche de I'Eucrine se trouve circonscrite par cinq levi'es. EUe ne se voit que 

 lorsqu'on a souleve ces cinq levres. On voit alors que c'est un petit trou rond d'en\iron 

 deux lignes de diametre. Les levres ne sont libres, et ne peuvent etre soulevees que de 

 trois lignes emiron. Dans le reste, elles sont adherentes par les cinq sillons qui partent 

 des commissures et se prolougent jusqu'a la circonference du disque. La mastication 

 ne s'opere pas par la bouche, mais bien par les levres, qui sont armees a cet eflet d'une 

 rangee de petites epines assez fortes. Quant a la nourriture, j'ai trouve des debris de 

 petits crustaces." This statement is important, since the imperfection of the specimen 

 of Pentacrinus described by Professor Muller prevented him from giving any account 

 of the parts about the mouth ; but the correspondence of the peripheral part of the disk 

 with that of Comatula led him to infer that the central portions are constructed on the 

 same plan, — the validity of which inference is confirmed by the description just cited. 

 It further appears from the reference made by our authors to the sketches of 

 M. DucHASSAijfG, that the mouth of Pentacrinus Caput-Medusoi is surrounded by Oral 

 plates, similar in form to those which exist in the Pentacrinoid larva of Antedon, 

 though no trace of them is to be found in the adult. I do not, however, regard the 

 evidence as yet sufficient to establish this conclusion. — In regard to the fossil Crixoidea, 

 MM. DE KoNiNCK and Le Hex made an important step in advance of their predecessors 

 in strongly drawing attention to the single, double, or multiple anal plate, as a peculiar 

 feature in the skeleton, introducing a bilateral symmetry in what would otherwise be 

 regularly radial. Their determination of the nature of this plate is fully borne out 

 by its position in the Pentacrinoid larva of Antedon, although, like the oral plates, it 

 is wanting in the adult. 



Of the recent systematic treatise by MM. Dujardin and Hupe on the Echixodermata 

 generally', it is only needful to say that whilst it furnishes a convenient resume of pre- 

 vious researches upon the Order Crixoidea and upon the genus Comatula (which, as 

 in D'Orbigny's arrangement, is taken as the type of a distinct Family, Comatulidce), it 

 adds nothing to our knowledge of them. In their systematic arrangement and descrip- 

 tion of the species of Comatula, these authors-for the most part follow Professor MtJLLEE. 



III.— EXTERNAL CHARACTERS, AND HABITS :— SYNONYMY. 



I. In common with other members of the Family CojiATULiD^, our Antedon may be 

 described generally as composed of a central disk, from which radiate ten slender arms, 

 fringed with pinnules along their entire length (Plate XXXI.). The disk contains 

 the whole of the proper Digestive apparatus, which forms a lenticular mass lying in the 

 hollow of a shallow calcareous basin or Calyx, and entii'ely exposed on its oral surface, 



' Histoire Naturello des Zoophytes Echinodermes, comprenant la description des C'rinoidcs, des Opliiurides, 

 des Asterides, des Ecliinides, et des Holothuiides. Par JI. E. Dujakbis et M. H. Hci'i:. (Suites a BufFon.) Paris, 

 1862. 



