Miscellaneous . 317 



these dorsal streaks are not the result of youth, and vanish as the 

 animal increases in size, as is the case with the Siren. 



T). While on these animals, I may observe, that Dr. Garden's 

 specimen of Siren that was originally described by Ellis, which is 

 now in the British Museum, shows a number of lines of mucous 

 pores on the chin and on the head, the latter not being so distinct 

 as the former, and a very distinct series of oblong white spots, 

 forming an interrupted line along the upper part of the sides of 

 the body, and continued to the middle of the sides of the tail ; 

 the spots on the hinder part of the body and tail being larger, more 

 distinct, and closer. These spots evidently represent the lateral 

 lines in Tritons and fish, and 1 have seen them mentioned in the 

 modern descriptions of the animal. 



MISCELLANEOUS. 



On the Vitality of Seeds transported by Marine Currents. 

 By M. C. Martins. 



Botanists, struck by the facts establishing the transport of seeds 

 by marine currents, have thought that the latter must have played a 

 great part in the diffusion of the disjoined species of plants which 

 form isolated colonies upon islands or continents separated by vast 

 extents of sea. Geologists, surprised at the uniformity of the vege- 

 tation of the great archipelagos scattered in the ancient seas, were 

 still more disposed to consider marine currents as the principal agents 

 in the dissemination of seeds upon the surface of the globe. These 

 k-priori conclusions have never been directly verified by experiment ; 

 — it has never been tried (1) whether many seeds are sufficiently 

 light to float upon saltwater; and (2) whether these seeds, after 

 floating for a long time at the surface of the sea, still retain their 

 germinative faculty. 



To settle this question experimentally, the author selected some 

 fresh seeds, of which the germination never fails, taking them from 

 the principal families, and generally preferring those of large size, 

 furnished with a hard and thick episperm, or those of littoral plants. 

 The former should resist the action of salt water, from their volume 

 and the impermeability of their envelopes ; the others should have 

 more chance of germinating if they fell upon a sandy shore. 



Of 98 species, 55 floated, and 39 were specifically heavier than the 

 water of the Mediterranean, the density of which, off Cette, is r0258. 

 Four seeds had a specific gravity equal to that of salt water ; these 

 are, Nehimbiian speciosum, Datura Stramonium, Juglans nigra, and 

 Gingko biloha. Thus, of a certain number of seeds taken by chance, 

 we may say that two-thirds float. 



To try the action of sea-water upon floating seeds, the antlior 

 endeavoured to place them in the same physical conditions to which 

 they would be subjected when floating at the surface of the sea. A 



