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
BioStor
