ISO 



MANUAL OF ZOOLOGY. 



to the interior of the calyx by a series of special apertures. 



(Billings.) 



More recently a stalked Crinoid has been discovered 



in the Atlantic and North 

 Sea, and has been described 

 under the name of Rhizocri- 

 nus Lofotensis (fig. 42). The 

 chief interest of this form is 

 the fact that it belongs to 

 a group of the Crinoidea 

 hitherto believed to be ex- 

 clusively confined to the 

 Mesozoic Rocks viz., the 

 ApiocrinidcB or " Pear-encri- 

 nites." In fact, Rhizocrinus 

 is very closely allied to the 

 Cretaceous genus Bourgue- 

 ticriniis, and it may even 

 be doubted if it is generi- 

 cally separable from it. The 

 late remarkable researches 

 into the life of the deeper 

 parts of the ocean have 

 brought to light several new 

 Crinoids, which will doubt- 

 less, when fully investigated, 

 still further fill up the inter- 

 val between the living and 

 extinct Crinoidea. 



In the second type of the 

 Crinoidea represented in 

 our seas by the Comatula 

 (fig. 43), or Feather-star 

 the animal is not perman- 

 ently fixed, but is only at- 

 tached by a stalk when 



Fig. 42. Crinoidea : Rhizocrinus Lofoten- vniin p- /ficr /<<? h\ in which 

 His, a living Crinoid (after Wyville Thorn- VOun g. V n S\ 43 h m 

 son), four times the natural size, a Stem, condition it Was described 



b Calyx. ccArms. as a Distinct species, under 



the name of Pentacrinus Europceus. In its adult condition, 

 however, the Comatula is free, and consists of a pentagonal 

 disc, which gives origin to ten slender arms, which are 

 fringed with many marginal pinnulse or " cirri." The mouth 

 and anus are on the ventral surface of the disc, which in this 

 case is again the inferior surface, since the animal creeps 



