Vol. XXvi] ENTOMOLOGICAL NEWS. 299 



Diatoms Attached to the Larvae. 

 While examining the larvae and exuviae of Thaumatoneura 

 the great number of diatom shells attached to them was very 

 apfwrent. A single leg, which had been detached from an 

 exuvia, was sent to Vrof. Albert Mann. Custodian in charge 

 of the Diatom Collection of the U. S. National Museum at 

 \\ .i>hingtoa, who has sent the following remarks on the dia- 

 toms adhering to this member: 



The •peciet discovered on this very mtntite quantity of material are 

 as follows: 



Aehnanthet ventruom Ehr. Eunctia mtmodou Ehr. 



Cocconeit placcnlula Fhr. Gamphontmm panttlmm Kg. 



and variety. Nmviada viridis Kg. 



CymbfUa vemtricosa .\g. ff. oblonga Kg., var. 



lipithrmia gibba (Ehr.) Kg. .V. n. sp. 



F.. gibhenOa (Ehr.) Kg. SiUsekia sp. 



E. sfbra (Ehr.) Kg. Pltwomgwf sp. 



and variety. Symtdrm uha (Niti.) Ehr. 



Of the foregoing. Epilhrmia srbrn is by far the most frequent. Com' 

 pkonttma parruimm next Symedrm mJma next. Ackmamthfs vmlrUom 

 next, and the others rather infrequent. The unnamed Sitssckia and 

 PUnromgwia afforded only one spec i men each aad their positioo was 

 such that I was unable to correctly identify dicni, bat I am quite coo- 

 fident that they are not new. The new NmvUtJa is extr e m e l y small and 

 very delicately marked, and I fortnnatdy have two specimens. 



I should say that there were at least S^o diatonu on the small leg 

 of this larva. The most of these are forms that grow attached by a 

 transparent jelly-like stipe ; bat several of them are free and free-mov- 

 ing—for example, the different species of Navicula. 



The finding of these forms on this aqnatic larva is of importance be- 

 cause it helps to throw light npoo a diffenk problem connected with the 

 distribution of diatoms. It has ahrays been more or less of a mystery 

 how isolated pools and bodies of water of recent origin become stodced 

 with a rather extensive diatom flora and frequently within a very short 

 period of time. Little is known regarding the spore formation of di- 

 atoms, investigations in this respect having been confined almost ex- 

 clusively to pdagic marine forms, such as Rkixosoltnio. In most of the 

 genera no spore formation has ever been discovered. Some light has 

 been thrown upon this distribution by supposing these organisms are 

 carried on die feet of wading birds, bat this method of transportation 

 is plainly very inadequate. If. however, we add to this transportati<m 

 by aquatic insects, many of which have the power of flying, we have 



