112 



It was found, on dissection, that the comatidcB have series 

 of calcareous secretions, or ossicula, exactly similar in their 

 general plan and arrangement to the crinoidea, and espe- 

 cially to the genus pentacrinus, and intended, like theirs, to 

 sustain muscular action : that, at the base of the subglobose 

 body of the comatulce there exists a pentagonal plate, ana- 

 logous in situation to the first columnar joint of the crinoidea ; 

 and an interesting affinity was found to exist between the 

 plates forming the pelvis oi coinatula, and of pe7itacrinus ; 

 and it was manifested that the auxiliary side-arms pro- 

 ceeding from the pelvis-like plate of cofnatula, the for- 

 mation of their joints, and their hook-like terminations, 

 resemble, in every particular, those of pt^^f^icinnus caput 

 medusae, only that they are much shorter, and formed of a 

 less number of joints. 



Having pointed out several other particular circum- 

 stances, proving the accordant structure of the comatida 

 and pentacrinus, Mr. Miller observes, that " The scapula 

 resemble also those of the pentacrinus caput medustz, but 

 are much more angularly pointed at their superior surface, 

 and are also tied laterally together by an integument. 



From each of the scapula in the different species pro- 

 ceed either two arm-like fingers, or two arms, each of the 

 latter formed of a common and cuneiform joint, from which, 

 on one side the first finger, and on the other a continuation 

 of the arm sets off, which, again, by the intervention of cu- 

 neiform joints, divides into two or more fingers, and then 

 forms a hand as in other crinoidea. Each joint of the arms 

 and fingers sends off, from alternate sides, a tentaculum, 

 formed of many articulated small joints, resembling, in for- 

 mation, those of pentacrinus caput medusae. An integument 

 extends over the abdominal cavity, the groove in the arms, 

 fingers, and tentacula, and is, like that in pentacrinus, also 

 protected by numerous minute calcareous plates*." 

 * Natural History of the Crinoidea, by J. S. Miller, A. L. S. p. 131. 



