352 NEW GEMUS OF ENCRINITES. 



Art. VIII. — On a recent species of Crinoidea, or Encriuites, con- 

 stituting the type of a new genus ; — Holopus.^ 



M. Alcide D'Orbigny, in a paper read before the 'Academie 

 des Sciences, ' at their sitting of February 27th, 1837, has de- 

 scribed a new genus of radiated animals, so interesting both 

 to the zoologist and geologist, that we have been tempted to 

 extract the descriptive portion of his paper from M. Guerin's 

 * Magasin de Zoologie' (where it is published), and to have 

 his plate engraved for our 'Illustrations.' 



The animal in question belongs to that section of the Ra- 

 diata, the species of which being destitute of the means of 

 locomotion, remain fixed to the ground ; and is allied to the 

 Pentacrinus europ(Bus, first described by Mr. Thompson:* 

 but differing in certain particulars from that species, M. D'Or- 

 bigny has been induced to constitute it a new genus, to which 

 he applies the name Holopus. The species is dedicated to 

 M. Rang, who discovered it at Martinico. 



HoLOPVS Rangii, D'Orbigny. Suppl. PI. xvii. 



Description. — External parts.- -B^oot enlarged, not ramose, 

 smooth, or but slightly marked beneath with intersecting 

 lines, which are irregular on its margins, and assume on the 

 under parts the form of the body on which the animal is fix- 

 ed ; foot or body thick, short, sub quadrangular, covered with 

 small rounded tubercles, which are most distinct on its angles ; 

 its surface, and that of all the external portions of the arms 

 (as viewed under a lens), exhibiting on all parts a finely stri- 

 ated or reticulated tissue, even on, the tubercles. Arms, four 



The Cucullanus foveolatus from the dah is perfectly white, of equal 

 diameter throughout, except at the extremities. The females are from 

 6 to Q\ lines in length, the males rather less ; the anterior extremity is 

 ohtuse, the posterior acute in hoth sexes ; the caudal extremity in the fe- 

 male is straight, incurved in the male. The cesophagus is longer and wider 

 than the stomach, it contracts suddenly where it joins the latter organ, the 

 stomach is cylindrical, the anus in the female is close to the caudal extre- 

 mity, in the male it is a little more anterior, and projects considerably; 

 the orifice by which the penis protrudes, is seated between the anus and 

 the caudal extremity. The penis is a double spiculum, very sharp, fine 

 and white ; the vulva in the female is situated nearer the caudal than the 

 anterior extremity. Several of the females, after remaining for a short 

 time in water (in which they at first moved about but soon died), ruptured, 

 and the intestine and ovaries protruded. 



1 Extracted from an article in Guerin's 'Magasin deZoologie,' for 1837. 



- 'A Memoir on the Pentacrinus curopceusy 4to. Cork, 1827. 



