692 DB. W. B. CAEPENTER ON THE STEUCTUEE, PHT8I0L0GT, AND 



specimen of Fentacrinus Caput-MeduscB transmitted by him from Guadaloupe. "La 

 bouclio de I'Encrine so tiouve circonscrite par cinq levres. Elle ne se voit que 

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

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

 trois lignes environ. Dans le reste, elles sont adhercntes par les cinq sillons qui partent 

 des commissures et se prolongent jusqu'^ la circonference du disque. La mastication 

 ne s'opore pas par la bouche, mais bien par les levres, qui sont armees a cet effet 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 Fentacrinus 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. DucHASSAiNG, that the mouth of Fentacrinus Ca^put-Medusas is surrounded by Oral 

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

 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 Ceinoidea, 

 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 symmetiy in what would othei-wise 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 Echln'odeemata 

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

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

 in D'Okbigny's arrangement, is taken as the type of a distinct Family, Com^tulidce), 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 foUow Professor MtiLLEE. 



III.— EXTEENAL CHAEACTEES, AND HABITS :— SYNONYMY. 



1. In common with other members of the Family CoMATULiD.iE, 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 

 hoUow of a shallow calcareous basin or Calyx, and entirely exposed on its oral surface, 



' Histoire Naturelle des Zoophytes Ecldnodermes, comprenant la description des Crinoides, des OpluTirides, 

 des Asterides, des EcMnides, et des Holothurides. ParM. F.DujABDiHetM.H. Hrri. (Suites a Buflfon.) Paris, 

 1862. 



