Miscellaneous, 319 



If, finally, we try to refer the number of species to the area of 

 each region according as it is more or less known, the regions, ac- 

 cording to their respective richness of forms, will stand thus : — 



1. Australian region = 1 : 33,000. 



2. Neotropical region = 1 : 50,000. 



3. Indian region = 1 : 66,000. 



4. Ethiopian region = 1 : 70,000. 



5. Nearctic region = 1 : 90,000. 



6. Palsearctic region = 1 : 250,000. 



MISCELLANEOUS. 



On the XJrticating Powers of the Actiniae towards each other. 

 By William Brodrick, Esq. 



The following facts may tend to illustrate the opinion held by 

 Mr. Gosse and others, that the " acontia " or missile-filaments which 

 so many of the Sea-anemones have the power of discharging when 

 irritated, are truly weapons of offence, and capable of inflicting injury 

 upon other animals, — an office which Mr. Lewes, in his * Sea-side 

 Studies,' altogether denied them. 



A large specimen of ^Sa^ar^m Dianthus, kept in a glass vessel together 

 with many other Actiniae and Madrepores, after remaining for some 

 weeks upon an oyster-shell, relaxed its hold and sought a fresh loca- 

 lity. In doing this it moved against a small light-yellow variety of 

 S. Bellis. At the point of contact, viz. the lower portion of the co- 

 lumn of the Dianthus, numerous acontia, entirely enveloping the 

 body of the Bellis, were discharged by the former animal : the Bellis, 

 when removed the next day, was quite dead. On the following night 

 the same thing occurred to a second and similar Bellis ; and on a 

 subsequent occasion, a >S'. Troglodytes and also a large specimen of 

 Caryophyllea Smithii were destroyed in a like manner. Upon exa- 

 mination under a ^-th object-glass, the discharged acontia, taken from 

 the bodies of the Bellis and Madrepore, were found to be those 

 peculiar to Dianthus, containing vast numbers of the "cnidae" 

 from which the long wire (ectkorceum) is projected. The majority of 

 these ecthorsea were somewhat altered from their usual appearance ; 

 the twisted — or, rather, waved — lower portion of the wire had a less 

 regular form ; and at the distance of about double the length of the 

 capsule from that organ, a series of barbs were observed, varying in 

 number from sixteen to eighteen. Not any of the shorter and more 

 densely barbed cnidse (somewhat similar to a bottle-brush) were 

 visible. The Bellis had also discharged its acontia ; these, however, 

 were very easily recognized as distinct from those of the Dianthus, 

 and did not appear to have penetrated, or in any way injured, the 

 body of that animal. In every instance the victims sloughed away 

 and became a mass of decomposition ; though, in the case of the 



