HOLOTIMIMA. 25 



tin- predominant colour above was reddwh-brown. Tlic suckers 

 are sometimes almost white, with u central red speck in their flattened 

 adhering extremities Tin' contracted tentacula of some are nearly 

 Mack. IVrhups it could be ascertained only by dissection, whether the 

 vaiue internal parts are always lowest in position where the pale under 

 )M>rtii>n. if it IK.- such, is applied to the Mistuining substance. 



So many features enter the characters of what I would conceive the 

 Hlthiirin ///////*, as certainly nn^ht to facilitate recognition of the 

 - . \et it seems to me, although I say it with reserve, that certain 

 discrepancies, apparently slight enough.aniong individuals, have prompted 

 naturalists to constitute two or three species of one : Nor is this the 

 only example of such an error, if it be an error, for the same has occur- 

 red of other Holothuruu. The whole subject, I repeat, is difficult ; yet 

 I fear that we create ambiguities by neglecting to shun them. 



No Holothuria is recovered from the sea fit for immediate study 

 All are disfigured or contracted ; some in one form, some in another 

 I'ntil relaxing into shape, adhering as a crescent, and displaying the 

 tentacula, nothing can be known of their nature. 



The skin of this species, the pentactes, is very coriaceous, hard and 

 thick, tough, and difficult to be penetrated when in a contracted state. 

 It becomes as thin as paper when the animal is distended, which is very 

 sensible in a specimen extending twelve or fifteen inches ; and it is more 

 evident in the higher and lower parts of one laid open. 



A very accomplished physiologist, Mr Henry Goadby, who had 

 devoted much attention to entomology, and the form of the invertebrate 

 animal-., visited Edinburgh in 1841, where he gave some excellent lec- 

 tures in illustration of the preceding subject. At that time I happened 

 to be occupied with the Holothuria, and as he expressed a desire to see 

 that animal, with which he had never had the fortune to meet pre- 

 viously, I had the gratification of supplying him with several fine speci- 

 mens of the pcntaclet. 



Of these he made various preparations and dissections, far surpass- 

 in); any that has ever been seen, both for minuteness and beauty, in 

 shewing the form, the multiplicity, and the arrangement of the parts. 



D 



