ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 209 



means, which accounts for the absence of reproductive organs. By its 

 habitat, its sterility, and its mode of multiplication, F. lutarius appears 

 to the author sufficiently distinct from F. veskulosus and F. axillaris. 

 He considers it is probably an adaptation of one of these two species to a 

 particular habit of life. This opinion is strengthened by the variation 

 in the distribution of the cryptostomata, which is not yet of a definite 

 character. 



Colpomenia sinuosa.* — L. Corbiere publishes a note upon Colpomenia 

 sinuosa, recording its presence at numerous stations on the coast of 

 Cherbourg as well as 20 kilometres to the west. He has no doubt that 

 millions of plants of it exist in the English Channel to the north of 

 Cotentin, though at the time of writing it had not been observed on 

 the oyster beds of St. Vaast. Specimens were collected at Les Flamands, 

 near Cherbourg, so long ago as March 1906. 



L. Mangin shortly discusses points of interest in connection with 

 this alga, and states that he has found it at St. Vaast among rocks to 

 the north and east of the Isle of Tatihou. It has also been found in 

 water of varying degrees of salinity, and the author hopes to give shortly 

 more information on the degrees of salinity and of brackish water in 

 which the plant can live. He points out that in certain states C. sinuosa 

 may be confused with Leathesia difformis ; but the former has a dense 

 cortex, composed of polyhedral cells closely adpressed, while L. difformis 

 has a filamentous external cortex, composed of cells easily separated. 

 The confusion can only take place in autumn, since Colpomenia appears 

 in autumn and winter, while Leathesia is a summer plant, appearing 

 in June. 



Lithothamnia of the ' Sealark ' Expedition.! — M. Foslie has worked 

 out the collection of Lithothamnia made by J. Stanley Gardiner in 

 the Chagos Archipelago, Saya de Malha Banks, Seychelles, and other of 

 the surrounding reefs and islands. He opens his paper with remarks 

 on the different species which occur in the different localities, and makes 

 interesting comparisons with the coral-reef building flora of other parts 

 of the world. He finds a close correspondence between the area in 

 question and the Maldives, the only region of the Indian Ocean which 

 has been well worked hitherto. It appears that three or four species 

 are the important reef -builders in the littoral region and in the upper- 

 most part of the sublittoral region. These are Lithophyllum onkodes, 

 L. craspedium and Goniolithon frutescens ; while L. Kaiseri (pallescens) 

 also contributes to the formation of reefs, and in depths of about 

 60 fathoms Lithothamnion indicum and L. australe play their part. The 

 author finds also that where Lithothamnia occur in great abundance, 

 covering entire atolls, the number of species is small, but the number of 

 individuals is enormous. This is the case at Chagos, Coetivy, certain 

 places in the Maldives, at the Ellice Islands (Funafuti), and at the 

 Gilbert Islands in the Pacific. In places where Lithothamnia do not 

 appear in such large quantities the number of species is much larger. 

 There seems to be a considerable correspondence between the Litho- 

 thamnia in the Indian Ocean and those in large areas of the Pacific 



l & v 



* Bull. Soc. Bot. France, liv. (1907) pp. 280-4. 



t Trans. Linn. Soc. (Bot.) ser. 2, vii. (1907) pp. 93-108 (2 pis.). 



