Zoological Society. 527 



With the exception of the genus Anguilla, the fresh-water species 

 are entirely absent, the physical structure of the island preventing the 

 formation of lakes and pools, and reducing its streams to the cha- 

 racter of rapid rivulets or mountain torrents. A result indicated by 

 the table just referred to, and which Mr. Lowe particularly notices, 

 is, that Madeira possesses as many species in common with Britain 

 as it has with the Mediterranean, and also that there is a variation 

 in the ratio between the marine Acanthopterygians and Malaco- 

 pterygians proportionate to the latitude. In Britain the marine ^caw- 

 thopterygians are to the marine Malacopterygians as one and a quarter 

 to one ; in the Mediterranean, as two and three fifths to one ; while 

 at Madeira the ratio increases to three and a half to one. 



The Author's remaining observations principally relate to the 

 particular periods of the year, and to the comparative abundance in 

 which certain species are met with. 



A Notice by Thomas Wharton Jones, Esq., was then read, " On 

 the mode of closure of the gill-apertures in the tadpoles of Batra- 

 chia." 



Mr. Jones observes, that when the right gill of the tadpole disap- 

 pears, it is not, as is usually supposed, by the closure of the fissure 

 through which it protrudes, but by the extension of the opercular fold 

 on the right side towards that of the left, forming but a single fissure, 

 common to the two branchial cavities, through which the left gill 

 still protrudes. He also remarks that conditions analogous to those 

 which occur during several stages of this process exist in the branchial 

 fissures of the anguilliform genera, Sphagebranchus, Monopterus, and 

 Synhranchus. 



April 11, 1837. — The reading of Mr. F. De Bell Bennett's paper 

 " On the Natural History of the Spermaceti Whale" was resumed ; 

 an abstract of which is given in No. Hi. of the Proceedings. 



Mr. Gould then called the attention of the meeting to a new and 

 beautiful species of Ortyx, a native of California, from the collection 

 of the late David Douglas, and characterized it under the name of 

 O. plumifera. 



He remarked that this genus was first brought before the Society 

 eight or nine years ago by Mr. Vigors, at which time only five spe- 

 cies were known, but since that period the number had been doubled ; 

 and from the remarkable development of the feathers forming the 

 crest in the species then exhibited Mr. Gould anticipates the dis- 

 covery of others, which shall connect Ortyx plumifera with those 

 species in which this character is less prominently shown. In sup- 

 port of this opinion Mr. Gould directed attention to the genera 

 Larus, Trogon and Caprimulgus, which possess certain characters 

 largely developed ; but the degree of development increases gradually 

 from the species in which it is least apparent to those in which it 

 attains its greatest extent. 



Mr. Gould then exhibited a new species of the genus Podar- 

 gus, from Java, which he proposes to name P. stellatus. 



Some observations on the Physalia, by George Bennett, Esq., 

 F.L.S., Superintendent of the Australian Museum at Sydney, and 



