292 Zoological Society : — 



paper last quoted, as by previous authors ; and the object of this 

 note is to direct attention to the support which the extended view 

 argued for by me in the paper above referred to, viz. that the finer 

 markings also correspond to depressions, derives from analogy. 



The structure of the Diatomaceae, and their modes of reproduc- 

 tion, are, as is well known, remarkable; — so much so, that these 

 organisms have been claimed by botanists as members of the vege- 

 table, and by zoologists as belonging to the animal kingdom. The 

 preponderance of evidence is decidedly in favour of their vegetable 

 nature ; but, be this as it may, they must all be classed together, — 

 they form a perfectly natural family. Hence we have a strong argu- 

 ment in favour of the markings upon their valves being identical, 

 and as these are evidently depressions in the genera and species with 

 coarsely marked valves (Istkmia, &c.), we should expect from ana- 

 logy that the same would apply to those with finer markings. And 

 this view receives further support, from the fact, that under varied 

 methods of illumination, corresponding appearances are presented 

 by the markings when viewed by the microscope, from those which 

 are very large, as in Isthmia, through those of moderate and small 

 size, as in the species of Coscinodiscus, down to those in which 

 they are extremely minute, as in the species of Gyrosigma, &c. The 

 angular (triangular or quadrangular) appearance assumed by the 

 markings, arises from the light transmitted through the valves being 

 unequally oblique. This may be readily shown in the more coarsely 

 marked valves {Isthmia, Coscinodiscus), which present the true 

 structural appearance when the light is reflected by the mirror in 

 its ordinary position, and the spurious angular appearance when the 

 light is rendered oblique by moving the mirror to one side. 



ZOOLOGICAL, SOCIETY. 



December 13, 1853.— R. C. Griffith, Esq., in the Chair. 



Descriptions of New Species of Bucconid^e. 

 By Philip Lutley Sclater, F.Z.S. 



1. Bucco RADiATUS, Sclatcr. B. sujyra dare ferrugineus, nigro 

 transverslm radiatus ; nucha et dorso summo pcene omnino 

 nigj'is ; corpore subtus et torque cervicali supra pallide fulves- 

 centi-albis ; capitis lateribus, pectore et ventris lateribus lineis 

 nigris transversim radiatis ; loris, gula, ventre medio crissoque 

 albis ; pedibus nigris ; rostro plumbeo. 



Long, tota 8*0 ; alee, 3*4 ; caudse, 3'0. 

 JIab. in Nova Grenada. Mus. Britannico. 



Obs. B. chacuru affinis, sed subtus radiatus et rostro plumbeo nee 

 rubro ; maculis auricularibus nullis. 



2. Bucco STRiATiPECTUS, Sclatcr. B. corpore supra nigrescentCy 

 alis caudaque magis brunnescentibus, omnino rufescente trans- 

 versim striatis ; capite nigro fere immaculato ; mento albo ; 

 gutture toto et collo undique fulvo-rufis ; pectore et ventris 



