ON THE ONYKIA ANGULATA. 299 



small, becoming larger near the extremity of the 

 range, particularly the exterior ones, of which the 

 longest are nearly two lines ; the interior range are 

 smaller, and placed at the base of the larger ones, 

 in order to replace them when they are destroyed ; 

 these hooks are moveable, straight, and compressed 

 at their base, and terminated by a curved point ; they 

 are covered by a whitish contractile membrane, open 

 at the extremity to admit the passage of the hook. 

 It appeared to me also, that this membrane was di- 

 vided at its base. Is this division for the purpose of 

 permitting a free pressure upon the dilated and per- 

 forated part at the base of the hooks, where is per- 

 haps hidden a venomous vescicle ? Besides, we re- 

 mark upon the sides of the hooks, where they are 

 naked, grooves, which are continued to the curve of 

 the hook ; this small opening may probably serve to 

 give a greater extent for muscular attachment. 



The interior bone is of a transparent bistre colour ; 

 its substance is horny diaphanous ; it is lightly ar- 

 quated, and of the form of a small elongated boat ; 

 its carina or ridge being stronger and darker, the 

 transverse section of its middle was in the form 

 of an open V, and was much closed towards the 

 posterior part of the bone, which terminated by a 

 small, elongated cup or hollow cone. 



The colour is very beautiful, as in all the species 

 of this genus, and occasioned by the numerous small 

 points, which cover all the body, the tentaculse, and 

 the arms. 



The figure is of the natural size 5 see plate. 



