2 Prof. W. Smith on the Diatomacese of the 



The following outline of my tour will show the extent of my 

 explorations, and I subjoin lists of the species that rewarded my 

 search. 



I reached Avignon on the 13th May 1854, and devoted several 

 days to an examination of the interesting localities in its imme- 

 diate neighbourhood, making gatherings of Diatomacese from a 

 well in the Amphitheatre at Orange, from the river Sorgues at 

 Vaucluse, and from the banks of the llhone near the spot where 

 it is joined by the waters of the Durance. Proceeding to Mar- 

 seilles, I spent three days on the neighbouring shores of the 

 Mediterranean, and collected from various spots north and south 

 of the city, many specimens of the larger Alga? rich in parasitic 

 Diatoms. A fountain in the court of the Hotel des Colonies, and 

 a spring near Chateau Vert also supplied abundant materials for 

 future examination. 



Returning from Marseilles, T made collections near St.Chamas, 

 on the borders of the Etang de Berre, a large salt-water lagoon 

 connected with the Mediterranean, and on the same day explored 

 the Canal de Crapone, in the vicinity of Aries. 



On the 24th May, I reached Montpellier, and found a few 

 specimens in the Chateau d'Eau, and the ponds of the Botanic 

 Garden, but was more amply rewarded during excursions which 

 I made from Montpellier to Frontignan, Cette and Agde, which 

 again brought me to marine and brackish-water habitats, under 

 the influence of the MediteiTanean. The Canal du Midi and 

 the river Herault also supplied a few valuable gatherings. 



Prom Montpellier my route lay through Nismes, where one 

 gathering, from the celebrated Pountain of the Nymphs, proved 

 rich in the number and variety of its forms. 



Prom Nismes I passed to Alais, and thence across the Cevennes 

 to the romantic city of Le Puy, collecting a few specimens at 

 Genolhac and Langogne, at an elevation of about 4000 feet. 

 The vicinity of Le Puy proved unproductive ; not so the neigh- 

 bourhood of Clermont-Ferrand, where I entered upon the vol- 

 canic region of Central France. 



Collections made from the " Fontaine Petrifiante,'^ or calcareous 

 spring of St. Alyre, and from basaltic caverns near the beautiful 

 village of Royat, lying at the base of the Puy de Dome, con- 

 tained many interesting species. 



Three weeks spent at the romantic watering-place of Mont 

 Dore les Bains, at an elevation of 3424 feet above the level of 

 the sea, enabled me to add to my herbarium most of the forms 

 which characterize the mountain springs and marshes of this 

 lofty region of extinct volcanos. The snows of the Pic de 

 Sancy, at an elevation of 6100 feet, snow marshes on the Pic du 

 Capuchin, and the shores of Lake Guery, a sheet of water which 



