72 MICROSCOPIC EXAMINATIONS OF AIR. 



of organic forms collected between February and September. A 

 careful study of these plates is interesting, but at the same time, 

 except in a few clearly marked instances, it would be extremely 

 hazardous to determine the species or genera to which they belong. 

 Undoubtedly there are many small globose or ovate spores which 

 might belong to Mucedines, but there are also a large proportion 

 of the peculiar dark coloured stalked spores of Macrosjjnrvmi, 

 some even in process of germination. Other spores have all the 

 ap})earance of Coryneum, and others again with a great resemblance 

 to Fhragmidium. Undoubted Pucciida spores ai)pear to be absent, 

 but the dark globose reticulated spores resembling "bunt" are 

 by no means uncommon, especially at the top of fig. 4, of plate iv. 

 There are a number of spores which greatly resemble those of 

 Hehninthosporium, and one on plate viii. is singularly like 

 HelmintJiospoi'ium Smithii, in size, form, and septation. The 

 spores in the preparation for July 24th, and for a month, 

 succeeding, are mostly in a state of active germination. Some 

 spores resemble those of Fusisporhnn and others of Diplodia, but 

 the only safe conclusion at which one can arrive from the 

 examination of the figures, is, that by far the larger proportion of 

 organic bodies consist of the spores of Fungi. In this light, 

 therefore, the report serves to confirm the fact, which has been 

 doubted, almost denied, of the presence of organic bodies to any 

 considerable extent in atmosplieric air. 



NEW GENUS OF DIATPMS. ' 



Mr. F, Kitton has characterised in the " Monthly Microscopical 

 Journal " for Kovember, a new genus of Diatomace^e, under the 

 name of Perrya, for forms which somewhat resemble Nitzschia, 

 but the compressed valve and absence of keel indicate that the 

 resemblance is only superficial. 



Perrya, Kitton. — Free, elongated, frustules compressed, some- 

 times slightly constricted, extremities rounded, striae transverse 

 moniliform. Marine. 



Terrya pulchexrima. X. — Valve in f. v. linear, inner or ven- 

 tral margin straight or very slightly concave, outer or dorsal 

 margin straight, suddenly rounded at the apices, markings distant 

 moniliform dots in transverse strise, s. v. narrow, linear, suddenly 

 tapering towards the acute extremities, a central line of large 

 moniliform dots dividing the valve Length "0090 to '0200, 

 breadth -OOlSin. — Kitton in M. M. Jown., Nov. 1874, p. 218, jjZ. 

 lxxxi.,Jig. 1. Nitzschia pidcherrima. Grunow ]\ISS. 



Hab. — Dredgings from Navy Bay, Colon, Panama; Campeche 

 Bay. 



Mr. Kitton intimates that he has found two or three other 

 species of the same genus, which he purposes describing hereafter. 



