Mat 12, 1911] 



SCIENCE 



751 



flowers are borne not near the apex, as in our 

 giant cereus of Arizona, but along the sides of 

 the branches and stems, often growing from 

 areoles of the older or lower joints, solitary, yet 

 often appearing from two or three adjacent are- 

 oles. The ripe fruits are very much like the 

 pitahayas sold in Mexican markets. They are 

 crowned by the withered perianth. 



The joints, appearing in series and separated 

 by abrupt constrictions, are sometimes five or six 

 feet long, shaped like great ears of corn, or like 

 thick-handled ten-pins or indian-clubs, or they are 

 shorter and oval, resembling a series of melons 

 piled one on top of the other, or they are some- 

 times spheroid, and the branches often form a 

 divarication from one of the globose articulations. 

 From the illustrations presented it is apparent 

 that the arboreous cereus of Chatham Island is 

 identical with that of Charles Island. It is to be 

 regretted that figures of the flowers of Galapagos 

 Cactaceas are absolutely wanting thus far, though 

 the islands have been repeatedly visited by scien- 

 tific expeditions. The older specimens of C. 

 thouarsU have stout cylindrical trunks covered 

 with bark which splits into longitudinal strips. 



The first description of an arboreous cereus 

 growing in the Galapagos is that of the navigator 

 Dampier, who visited the group in 1684. He de- 

 scribed it as "a, green prickly shrub ten to twelve 

 feet high, as big as a man's leg and fuU'of sharp 

 prickles in thick rows from top to bottom, but 

 without leaf or fruit." Colnett, in 1793, distin- 

 guished the cereus from the opuntia observed by 

 him in the Galapagos, calling the first a ' ' torch 

 thistle ' ' and the second a ' ' prickly pear. ' ' 



Captain David Porter was the first writer to 

 call attention to the differences of the tortoises on 

 the different islands of the Galapagos. His jour- 

 nal of the Essex was published twenty years be- 

 fore the visit of the Beagle. Figures were pre- 

 sented of two of the living tortoises from the 

 Galapagos now in the National Zoological Park, 

 Testudo epMppmm, an example of what Captain 

 Porter called the saddle-backed form, and Testudo 

 vicina Guenther, with a back of the form likened 

 by Woods Eogers, the old sea-rover, to the top of 

 an old-fashioned hackney coach. 



The figure of a fossil species, Testudo oshorni- 

 ana Hay, from the Miocene of northeastern Colo- 

 rado," was also shown, and the question as to the 

 possible connection of the Galapagos group with 

 the main land during some part of the Tertiary 

 age was discussed. The fact recorded by Captain 

 Porter that tortoises thrown overboard from cap- 



tured vessels remained floating and unharmed for 

 several days, though unable to swim, was cited as 

 bearing upon the point of the possible translation 

 of the ancestors of the tortoises from the conti- 

 nent to the islands by ocean currents. 



The paper ended with an account of the writer 's 

 visit to a hermit living in a cave in the interior 

 of Charles Island, and of the animals which had 

 become wild on the island, some of which had been 

 caught when young and domesticated by the her- 

 mit. An account of the garden cultivated by the 

 hermit was also given. 

 The Keys, Corals and Coral Reefs of Florida: 



T. Wayland Vaughan. 



Dr. Vaughan gave a short lecture, illustrated 

 by stereopticon views, on the subjects indicated by 

 the title of his communication. He called atten- 

 tion to the extensive submarine plateau, of which 

 the present land surface of Florida constitutes 

 less than one half, and lies near the eastern mar- 

 gin. He briefly described the course of the 100- 

 fathom curve and the steep declivity from it to 

 the depth of 1,500 and 2,000 fathoms in the Gulf 

 of Mexico, whereas between peninsular Florida 

 and Cuba (except north of Havana) the depths 

 are less than 500 fathoms. Between the northern 

 end of the Bahama bank and the east coast of 

 Florida the depth is somewhat less than 300 fath- 

 oms. The course of the 10-fathom curve was 

 traced, and the relations it bears to the great 

 barrier reef of Florida were indicated. The Hawk 

 Channel, which lies between the line of reefs and 

 the keys, the keys, and the bays and sounds be- 

 tween the keys and the mainland, were briefly 

 described. A series of photographic slides were 

 shovm to illustrate the topography and geology of 

 the mainland in the vicinity of Miami, and the 

 surface features, including the vegetation, of the 

 entire line of the Florida keys. The geologic 

 formations of the region are of Pleistocene or 

 recent age. The keys from Virginia Key at the 

 north to Bahia Honda are elongated in a cvirve 

 from northeast to southwest. Then follows the 

 second group of keys including the Pine Keys, 

 and extending to Boca Grande west of Key West 

 are elongated in a direction at right angles to the 

 axis of elongation of the more northerly keys; 

 while the Marquesas and the Dry Tortugas are of 

 atoll form. In composition the keys opposite the 

 northern end of Bay Biseayne have a surface 

 largely of siliceous sand. Those from Soldiers 

 Key to the southern end of Big Pine Key are 

 composed of elevated coral-reef rock — the Key 

 Largo limestone. The keys from the Pine Keys 



