OcToBER 23, 1902] 
sections of the earlier stages by affixation of the egg to the 
embryonic membrane of the pig. (2) Prof. J. C. Ewart gave 
an account, illustrated by the lantern, of some recent inter- 
crossing experiments with dogs. and pointed out that unless one 
of the parents was highly prepotent, the first crosses were not as 
a rule uniform, and that when the members of the cross-bred 
litters were interbred, some of the offspring very closely 
resembled the pure-bred grandparents. (3) Mr. Nelson 
Annandale had a paper on flower-like insects from the Malay 
Peninsula, and Mr. H. C. Robinson, who had been on the 
same expedition, gave notes on protective resemblance—both 
subjects being illustrated by lantern slides. (4) Prof. Poulton 
then gave lantern exhibitions (1) of British insects in their natural 
attitudes, and (2) of three-colour slides showing mimicry, 
protective resemblance, seasonal forms of butterflies, &c. 
(5) Mr. Thos. Steel exhibited an interesting collection illus- 
trative of Australian zoology, such as the different species of 
Peripatus, including forms of Ooperipatus which lay fertile 
eggs having a lengthy period before hatching; also a fine 
series of land Planarians, also marsupial embryos, the blind 
marsupial mole, WVoforocytes typhlops, and the honey ant, 
Camponotus inflatus, both from the Central Australian desert. 
(6) Prof. R. J. Anderson gave two notes—one on a specimen 
of the pilot whale of a white colour, with twenty-eight teeth 
and a large foramen of Winslow in the abdomen; and the 
second on the relations of the parietal bone in Primates. He 
showed that the orang is in a variable condition, having some- 
times, but not always, a parieto-sphenoidal suture. Other varia- 
tions were discussed. (7) Mr. A. T. Watson gave a most 
interesting account, illustrated by the lantern, of the errant 
habits of the Onuphidz (Polychzta), and described a defensive 
mechanism which he had discovered in the tubes. The onuphid 
worms drag their tubes over the sea-bottom, and protect 
the open ends by constructing membranous valves, like those 
of the veins, and so arranged that on retreat of the worm the 
inrush of sea water causes the valves to close automatically. 
(8) Mr. R. T. Leiper, on an accelous Turbellarian inhabiting 
the common heart urchin. The worm was found in the 
accessory canal of about 5 per cent. of the Achznocardium 
cordatum at Millport. It is white, leaf-like, and 2°5 mm..in 
length. Thereis no spermotheca or vagina. A similar absence 
of female accessoria obtains in Haplodiscus, from which this 
Turbellarian differs in the following respects:—(1) shape; (2) 
parasitic habitat ; (3) mouth in anterior fourth; (4) paired 
lateral testes ; (5) no defined vasa deferentia; (6) penis with 
chitinous knob-like armature; (7) large digestive vacuole. In 
discussing the classification of the Accela, the author suggests 
that the family Proporidz, comprising all Accela with one 
genital opening, be subdivided to form two subfamilies :—(1) 
Proporinz, to include the genera (a) Proporus, (6) Monoporus, 
(c) Bohmigia, z.e. those with a common genital pore; (2) 
Avagininz, consisting of (z) Haplodiscus and (4) the genus now 
recorded, z.e. those having a male pore only. The name 
Avagina incola is proposed for this new form. 
On the Tuesday, Dr. Henry Woodward gave a note on a 
diagram of the skull of Mastodon angustidens. Dr. R. F. 
Scharff had an interesting paper on the Atlantis problem, in 
which he collected a number of facts in the distribution of 
animals bearing upon the possible land connection between 
Europe and America by way of the Atlantic islands. His in- 
vestigations tended to show that Madeira and the Azores are the 
remains of an ancient Tertiary area of land which was joined to 
Europe, and that it probably became disconnected in Miocene 
times. As toa land bridge across the Atlantic, many reasons 
can be given in its favour. Uniting North Africa with Brazil 
and Guiana in early Tertiary times, it probably subsided during 
the Miocene period, leaving only a few isolated peaks as 
islands. 
Mr. R. J. Ussher gave an interesting address, illustrated by 
lantern photographs taken by Mr. R. W. Welch, on the 
avifauna of Ireland as affected by its geography. He shows 
that as a result of the position and features of the country, some 
species breed more numerously and extensively than in Eng- 
land. The buzzard, bittern and capercaillie have been exter- 
minated, and certain other British birds have never established 
a footing in Ireland. Winter and occasional visitants were dis- 
cussed, also the list of North American species taken in Ireland. 
The ‘raven, harriers and eagles are approaching extinction. 
The bones of the great auk found in kitchen middens in Antrim 
show that it was used as food. 
NO. 1721, VOL. 66] 
NATURE 
641 
Mr. E. J. Bles gave two communications, one on the develop- 
ment of Xenopus, and the other on experiments on the Axolotl, 
showing adaptations to life in an alkaline medium. Dr. H. W. 
Marett Tims had a paper on the structure of the scales in the 
cod. Prof. C. S. Minot, of Boston, U.S., gave an address 
on the significance of the embryonic cell, in which he gave the 
results of his observations on cellular development in guinea- 
pigs, mice and rabbits. Mr. J. Stanley Gardiner had a paper on 
the breaking up of coral rock by organisms in the tropics. First 
the boring algce and sponges penetrate the living corals, extend- 
ing into every septum and spine. They weaken the coral and 
so riddle it that it is then easy for boring Polychzeta such as 
Polydora and Eunice to enter. Following these come various 
Sipunculids, the bivalve Lithodomus and the cirripede Lithotrya. 
Then a wave breaks off the coral mass, leaving a bare sur- 
face, which more boring animals at once take advantage of. 
The fallen coral mass is finally broken down into smaller and 
smaller fragments by the boring animals. Then the sand- 
feeders come into action and grind up the coral fragments into 
sand. Chief among these may be mentioned the sea-slugs, 
Holothuria atra and Stichopus chloronotus, which appear to 
retain within their guts the coarser fragments in the sand for long 
periods of time, while the finer particles are swept out along 
the ciliated grooves. Other sand-feeding forms are Sipunculus, 
Echinus and Ptychodera, the mound-like casts of the latter of 
which form most conspicuous features of the landscape at low 
tide. Much of the finer material must pass into suspension in 
the water and be swept out by the tidal and oceanic currents, 
while the smaller the sand grains the greiter the area they pre- 
sent for solution. It will thus be clear what an important bear- 
ing the sand-feeding and boring animals have on the formation 
of the lagoons of atolls. 
Mr. J. Graham Kerr communicated a paper, illustrated by 
microscopic preparations, on the early development of muscles 
and motor nerves in Lepidosiren. He described a stage in 
which the inner wall of the myotome consisted of a layer of 
large neuromyoepithelial cells, the cell substance of each of 
which was continued into a tail-like process, which was in turn 
continuous with the nerve rudiment. The outer wall of the 
myotome was shown to contribute largely to the formation of 
the myomere. Mr. Kerr’s preparations showed that the con- 
nection between spinal cord and myotome existed at a very 
early period—while the two structures were still in contact—and 
that these primitive connections—the rudiments of the motor 
nerve-trunks—became gradually drawn out and lengthened 
as the myotome receded from the spinal cord with the inter- 
position of mesenchyme. The motor nerve-trunk, at first naked, 
became later on surrounded by a sheath of mesenchymatous 
protoplasm. 
Mr. G. H. Carpenter, of the Dublin Museum, read a paper 
on the insect fauna of some Irish caves, dealing especially with 
Collembola discovered in Michelstown Cave, co. Tipperary, 
and in Dunmore Cave, near Kilkenny. With the exception of 
Heteromurus margaritatus, Wankel, which has now been found 
to inhabit caves in Ireland, France and southern Austria, all the 
blind species enumerated occur in above-ground localities (albeit 
with a discontinuous range) as well as in various caves in con- 
tinental Europe. These facts point to the conclusion that such 
insects may be regarded as the survivors of ancient races with 
wide distribution whose ancestors were destitute of eyes; now 
almost exterminated in the upper world by the competition of 
eyed forms, they still survive in the caves. This conclusion 
does not, of course, contradict the generally accepted view that 
a large proportion of the blind cave fauna of continental Europe 
and North America (probably including . #zargart/a/us men- 
tioned above) must be descended from eyed ancestors. 
On Wednesday forenoon there was an interesting discussion 
on natural selection in relation to protective resemblance and 
mimicry in animals, arising out of the communications made to 
the section by Prof. Poulton and by Messrs. N. Annandale and 
H. C. Robinson, Prof, Poulton, in opening the discussion, 
expressed his conviction that natural selection was the key to 
the puzzle, although it was not always possible to say how it 
should be applied. He gave examples of some mistakes that 
had been made in the past, and since rectified in attributing 
utility to characters. He alluded to the results he had obtained 
from the destruction of chrysalides in different environments, 
and he finally accepted natural selection as a working theory, 
Mr. Annandale and Mr. Robinson both brought up various 
cases observed by them in {Siam and Malaya where the 
