the Fauna oj Biomeliaceae. 429 



insects. The finding o£ the Aglymbus is special!}'- interesting 

 in connection with tlie previous discovery, already referred to 

 above, of a tree-inhabiting species of the allied genus 

 Copelatus in the Old-World tropics — i. e. Copelatus panda- 

 norum, which lives in the water between leaf-bases of Pan- 

 danus in the perennially moist mountain-forests of the 

 Seychelles. Beyond these two species I am unaware that 

 any Dytiscid has been found inhabiting trees. The larva3 of 

 Helodinse are aquatic, e. g. those of Helodes minuta live 

 beneath stones submerged in streams ; and Microvelia 

 belongs to a group the members of which run on the surface 

 of fresh water. As to the Hydrophilid, the members of the 

 genus Cyclonotum might be described as subaquatic, most of 

 them appearing to live in decaying vegetable refuse which 

 often contains much moisture. Shelford has called attention 

 (below^) to an adaptation of the new cockroacli (Homalo- 

 pteryx) for an amphibious existence. In this connection 

 nothing can be said at present with regard to the Tricho- 

 pteryx or the Eupathithrips ; but the facts just summarized, 

 in conjunction witli the presence of the frogs, show the 

 aquatic or amphibious nature of the bromeliadicolous fauna. 



It may be asked if the truly aquatic insects show any 

 special adaptation for living in the Bromeliacese as compared 

 vvith their congeners which inhabit w^aters on the ground. 

 The Aglymbus is more flattened dorso-ventrally than its con- 

 geners, this being perhaps an adaptation for living in the 

 narrow spaces between the leaf-bases [Copelatus pandanorum 

 is also flattened). I am unaware of any special adaptation in 

 the Microvelia. The Helodine larvae are less flattened than 

 those of Helodes minuta, which live under stones ; and 

 Prof. Carpenter considers the bromeliadicolous larvie the less 

 specialized of the two (see below). 



In a letter to me Mr. Urich writes : — " If these beetles 

 [the Aglymbus'] are confined to higher elevations and must 

 live at the tops of our highest hills, then they are entirely 

 confined to Bi'omelia-\v eiter, as the tops of several hills of the 

 Northern Range appear to have no other water " within a 

 mile of the summit by road, or, vertically, above 2500 feet *. 

 Mr. Urich refers to the fact that, although there is extremely 

 abundant moisture on the mountain-tops, yet there are no 

 pools or streams, and the only water in which truly aquatic 

 insects such as Dytiscidse could live is that which collects 

 between leaf-bases, in inflorescences, &c. The same state- 

 ment applies to the highest parts of the Seychelles forests ; 



* Mr. Urich adds that he has seen frogs similar to those found by us 

 in the same kind of bromeliad at similar elevations on other peaks. 



