530 Meeting of the British Association. [Oct., 
they did. They only proved the existence of a vast sheet of or- 
ganized matter at this great depth, which he suggestively had spoken 
of as “Urschleim.”  ~ 
In a very detailed communication “ On the Boring of certain 
Annelids,” Dr. McIntosh controverted the chemical theory of 
erosion suggested last year, at Dundee, by Mr. Lankester in 
reference to these animals. He exhibited specimens of shale which 
he asserted were not calcareous, nor subject to erosion by acids, and 
which were yet perforated by Leucodore. Mr. Ray Lankester in 
commenting on this paper, maintained that his inference from 
the evidence which had come before him last year, was at the time 
ajust one.* The presence of an acid must be an important auxiliary 
in the erosion of limestone rocks, though loose shales could be bored 
mechanically. Dr. McIntosh’s figures of the bristles of Lewcodore, 
he showed, were erroneous. 
Dr. McIntosh also gavea short account of the Annelids dredged 
by Mr. Gwyn Jeffreys im Shetland. 
Among anatomical papers, that of Mr. Flower “ On the Homo- 
logies and Notation of the Teeth of the Mammalia” was one of 
great importance. He had discovered that some of the so-called 
monophyodont mammals, namely the Armadilloes, had a complete 
set of milk teeth preceding those with which they were provided 
when adult; further he had shown, recently, that in marsupials 
only one tooth, the so-called fourth premolar, has a successor, 
whilst in dogs only one or two at most of the premolars have 
predecessors. In seals, the first set of teeth were extremely 
minute, mere points of tooth substance, and this led to the belief 
that they were evanescent. From these facts and others of a 
similar nature, Mr. Flower concluded that the so-called milk or 
first set of teeth is by no means to be regarded as the typical or 
chief series as Professor Owen had supposed, to which the second 
set are a super-addition ; but on the contrary, the milk-teeth are 
something added to the normal dentition in the higher mammalia, 
and more especially in those groups which require teeth when 
young. In the discussion on this paper, in which Professors 
Huxley and Rolleston took part, an interesting question was raised 
as to whether the evanescent condition of the milk-series of teeth in 
the seals did or did not indicate an approach to the condition of the 
Cetacea, which have but one set, that 1s are Monophyodont. 
Professor Rolleston, in a paper “On the Pectoral Muscles,” gave 
his conclusions as to the homologies of the muscles of the upper 
arm and chest in Mammals, Birds, and Reptiles. He also dis- 
* See ‘Quarterly Journal of Science,’ October, 1867. 
