COLLECTING AND PRESERVING 309 



this to dry. It will, of course, show a little white in any 

 case, but the Echinoderms are not black. 



The Sea-urchins (Echinodea) must be emptied out, and 

 they should be preserved as soon as taken, or the spines 

 will lose their rigid radiation, and lie lax and unnatural. 



It is a good plan to plunge them into strong spirit as soon 

 as brought home. In this they can be left for any length 

 of time, before proceeding further. For cleaning out, the 

 " Aristotle's lantern " is removed, by passing a penknife 

 through the surrounding membrane. Then the inside is 

 taken out with a hooked wire and forceps, the inside well 

 washed under the tap a bottle brush is of service. Then 

 rinse in the corrosive sublimate, and put out to dry. The 

 " lantern " can be rinsed in corrosive, and set alongside on 

 the final mount. 



To obtain the " Test " denuded of its spines, as in Fig. 

 32, it is the easiest plan to boil them ; the spines will 

 come off readily, a fluff of membrane and the ends of the 

 ambulacral feet will prove adherent, but a stiff nail brush 

 and the water tap will remove these. 



The Holothurians. The " Sea-cucumber " is somewhat 

 difficult to kill with the tentacles extended. The best 

 plan is to treat these as directed for zoophytes, and then 

 to place in spirit, in a jar of suitable size, either free or 

 fastened to a mica plate. 



Synapta has the habit of constricting itself into the form 

 of a little string of sausages and then breaking up into 

 chunks, which makes it difficult to preserve specimens for 

 fair display. This may be obviated in a great measure 

 by bringing them home in sea-water, and then dropping 

 them, horizontally, into a dish of strong spirit. The 

 tentacles are never fully, but still they are partially, ex- 

 tended. 



The Vermes. These must be treated with great care to 

 make good exhibits. It will not do to plunge them into 



