STOMACH, BODY, ARMS, AND FINGERS OF PENTACEINITE. 331 



Stomach. 



The abdominal cavity or stomach, of the Pentacrinite, 

 (PI. 51, Fig. 2.,) is rarely preserved in a fossil state; it 

 formed a funnel-shaped pouch, of considerable size, com- 

 posed of a contractile membrane, covered externally with 

 many hundred minute calcareous angular plates. At the 

 apex of this funnel was a small aperture, forming the mouth, 

 susceptible of elongation into a proboscis for taking in food.* 

 The place of this organ is in the centre of the body, sur- 

 rounded by the arms. 



Body, Arms, and Fingers. 



The body of the Pentacrinite, between the summit of the 

 column and the base of the arms, is small, and composed of 

 the pelvis, and the costal, and scapular plates, (See PI. 51. 

 PI. 52. Fig. 1. 3. and PI. 53. Fig. 2. 6. E. F. H.) The arms 

 and fingers arc long and spreading, and have numerous 

 joints, or tentacula ; each joint is armed at its margin with 

 a small tubercle or hook, (PI. 53. Fig. 17.,) the form of 

 which varies in every joint, to act as an organ of prehen- 

 sion ; these arms and fingers, when expanded, must have 

 formed a net of greater capacity than that of the Encri- 

 nites.f 



We have seen that Parkinson calculates the number of 

 bones in the Lily Encrinite to exceed twenty-six thousand. 



• This unique specimen forms part of the splendid collection of James 

 Johnson, Esq. of Bristol. 



f The place of the Pentacrinites in the flimily Echinoderms, would lead 

 us to expect to find minute pores on the internal surface of the fing-ers, analo- 

 gous to those of the more obvious ambulacra of Echini; they were probably 

 observed by Guettard, wlio speaks of orifices at the terminating points of 

 the fingers and tentacula. 



Lamarck also, describing his generic character of Encrinus, says: "The 

 branches of the Umbel are furnished with Polypes, or suckers, disposed in 

 rows." 



