DEEP SEA FAUNA 1317 



stem five little calcareous lumps like buttons stand 

 out from the projecting ridges, and upon these and 

 upon the upper part of the stem the cup which holds 

 the viscera of the animal is placed. 



All the ordinary joints of the arms are provided 

 with muscles producing various motions, and bind- 

 ing the joints firmly together. If one of the arms 

 get entangled, or fall into the jaws or claws of an 

 enemy, by a jerk the star-fish can at once get rid o*f 

 the embarrassed arm ; and as all this group have a 

 wonderful power of reproducing lost parts, the arm 

 is soon restored. 



Unfortunately, most of the examples of Penta- 

 crinus asteria hitherto procured have had the soft 

 parts destroyed and the disk more or less injured. 

 One specimen, however, in my possession is quite 

 perfect. The body is covered above by a membrane 

 closely tessellated with irregularly formed flat plates. 

 The mouth is a rounded opening of considerable size 

 in the centre of the disk, and opens into a stomach 

 passing into a short curved intestine which ends in 

 a long excretory tube the so-called "proboscis" of 

 the fossil crinoids which rises from the surface of 

 the disk near the mouth. From the mouth five 

 deep grooves, bordered on either side by small square 

 plates, run out to the edge of the disk, and are con- 

 tinuous with the grooves on the upper surface of the 

 arms and pinnules, while in the angles between them 

 five thickened masses of the mailing of the disk 

 surround the mouth like valves. These were at 

 first supposed to answer the purpose of teeth. The 

 crinoids, however, are not predatory animals. Their 



