Principal J. W. Dawson on Eozoon canadense. 29 



Ohs. The structure of the antennae, as well as their insertion, 

 seems to justify the location of this insect in the Colydiidse. 

 The anterior cox£e are very small, and their cavities completely 

 closed behind ; and this is the only character, so far as I can 

 see, which would throw any doubt on the propriety of the asso- 

 ciation mentioned. Mr. Wollaston, in calling attention to the 

 peculiarities of this important genus, has already suggested its 

 affinity with the Colydiidee. The New-Zealand insect I have 

 here described approaches the Aglycyderes setifer closely in 

 appearance ; but it differs in the structure of the antennee, 

 as well as in its remarkably widely separated anterior coxa3. 

 The Colydiidaj as a group is one of the less specialized of the 

 Coleopterous gi-oups ; and it is not therefore surprising that 

 we should find some of its members exhibiting wide and 

 puzzling affinities. I am unable to see any close relationship 

 in Aglycyderes with Brucliidffi and Anthribida3 ; and if the 

 genus be not accepted as an aberrant member of the Colydiida^, 

 I think there is no other course but to do as Mr. Wollaston 

 has suggested, viz. to regard it as representing a distinct 

 family of Coleoptera. 



III. — Eozoon canadense, according to Hahn. 

 By J. W. Dawson, LL.D., F.R.S., F.G.S. 



We may probably expect, for some time, to find enthusiastic 

 mineralogists suggesting plausible theories to account for 

 Eozoon by purely physical causes ; for the doctrine of " plastic 

 force " is not yet extinct in this particular case. Hahn's recent 

 memoir is one of these efforts, and is certainly creditable to 

 his ingenuity and boldness, more especially as it is quite at 

 variance with the hypothesis advocated by Messrs. King and 

 Rowney. It is, however, in my judgment, so improbable that, 

 but for the sanction given to it by a translation into the 

 'Annals,' and for the new statements which it makes as to 

 certain histological facts, it would scarcely merit a serious 

 discussion. Yet it affords an opportunity to notice a number 

 of minor points respecting Eozoon^ which, though not over- 

 looked by those who have studied it, have not been brought 

 prominently forward, lest they should confuse the minds of 

 geologists as to essential facts. 



Hahn's explanation refers only to the specimens of Eozoon 

 mineralized with serpentine, the only specimens which he 

 appears to have studied. It does not apply to those minera- 

 Tized with calcite. Dolomite, Loganite, or pyroxene, except in 

 so far as the cases of these ma}- be supposed to be covered by 



