KEPORT ON TIIE DIATOMACKEL 57 



Plate XXV. fig. 11, represents two Fragilarian valves, the first of which belongs to the 

 new Fragilaria linearis 1 above described, but the determination of the second, which 

 is of lanceolate form and differs markedly in its striation, is uncertain, as nothing except 

 the valve is known. 



The frustules seen at fig. 17 of the same plate must also remain undetermined. They 

 possess a very elegant oblongo-lanceolate form, are provided with acute apices, and are 

 transversely marked with alternating light and dark zones. These rare specimens were 

 found in mud obtained from a sounding in the neighbourhood of Japan, and their charac- 

 teristic features are not yet fully known. 



Diatoma, De Candolle. 

 Diatoma rhombicum, O'Me. (Plate XXV. fig. 22.) 



We have here represented a small elliptical valve, which was found in a gathering 

 made to the south of Heard Island. In a paper on the Diatomaceous Gatherings made at 

 Kerguelen Island, by O'Meara, and published in the Linnean Society's Journal (Botany), vol. 

 xv., this frustule is seen on Plate i. fig. 2. Of the accuracy of the generic determination 

 there can be no doubt, especially as O'Meara has also figured a series of many frustules 

 disposed in a zig-zag manner, nor can there be any question as to the identity of the 

 Diatom now represented with O'Meara's specimens. The definition given of the typical 

 Diatom is as follows : " Frustules small, about -000G in length. On front view quad- 

 rangular, the costse appearing as a narrow band of puncta. On side view rhombic ; costae 

 very fine, pervious." 



Grammatophora, Ehrenb. 



Grammatophora stricta, Ehrenb., var. nov. (Plate XXIX. fig. 12.) 



"We have here represented the only frustule belonging to this genus which calls for 

 particular attention, and which was collected in the Sea of Japan. It is closely related to 

 the Grammatophora stricta of Ehrenberg, 2 as figured by Kiitzing in his work entitled 

 Die kieselschaligen Bacillarien oder Diatomeen, Plate xxix. fig. 76 ; but the latter is 

 somewhat larger, the septa are not so straight, and at the polar extremities these are not 

 flanked by a small appendage. Such points of difference, however, cannot be regarded as 

 of more than varietal importance. 



Cyclophora, n. gen. 



In February 1878 I read before the Pontifical Academy 3 a communication, in which 

 I made known a new Tahellaria, which I had met with some years before adhering to 



1 Compare Plate XIX. fig. 9. 



2 Ehrenb., Verb. T. L i. fig. 22, and T. III. vii. fig. 31 ; Eabenhorst, Flora Europaea Algarum, p. 305. 



3 Atti. Accad. Pontif. d. nuov. Lincei, 1878. 



(bot. chall. exp. — part iv. — 1886.) D 8 



