Oct. 28, 1886] 
pleted, especially as our knowledge of the changes is too limited 
to permit of the use of Ross’s observations. Further it is desir- 
able to have actual verification of Gauss’s extension by theory of - 
the magnetic elements at places where they are known to places 
where they are unknown. The position of the south magnetic 
pole is still undetermined, and magnetic observations are wanted 
from 40° S. to the geographical pole. For the carrying out of 
these views, Melbourne Observatory, being furnished with the 
necessary instruments, would serve admirably as a base station, 
with subsidiary bases at the Cape, and at Sandy Point, Magellan 
Strait, for the use of portable absolute instruments. Much of 
the survey could be done on board ship at sea, observations | 
| hypothetical lateral fin; (¢) the blood from both appears to be 
having now become so trustworthy by the process of “swing- 
ing ship.” Portable instruments could also be used on “ce, 
where their readings would be specially free from sources of 
error. The great effect of the ship’s iron in high latitudes can 
be got rid of by experience, as proved in the voyage of the 
Challenger, an important matter being a proper position on 
board far the instruments. This position could be chosen im- 
mediately after the selection of the ship. The error in the 
vertical component varies with the ‘‘heel” of the ship; the 
horizontal error can be eliminated by the process of ‘‘ swinging.” 
NOTES FROM THE OTAGO UNIVERSITY 
MUSEUM 
VIII. — Ox the Claspers of Callorhynchus 
IX my friend Mr. Patrick Geddes’ able article, “* Reproduction,” 
published in the recently issued twentieth volume of the 
‘* Encyclopedia Britannica” (ninth edition), the following note 
occurs (p. 410) :— 
‘In the curious Holocephalous fish, Cal/orhynchus, Jeffery 
Parker has recently adduced arguments for regarding the claspers 
as the surviving rudiments of a third pair of limbs.” 
As this passage was written under the mistaken impression 
that a somewhat wild theory, hither only communicated privately 
to one or two friends, had been published, I think it will be 
advisable to state exactly the grounds on which I am disposed, 
provisionally, to consider the Holocephali as the only existing 
hexapodous vertebrates. 
In the Elasmobranchii (Plagiostomi) the male is well known 
to possess a single pair of so-called claspers, each having the 
form of a plate rolled longitudinally upon itself so as to produce 
an incomplete tube, and supported by a more or less complicated 
cartilaginous skeleton continuous with the basipterygial cartil- 
ages of the pelvic fin. 
In Callorhynchus, on the other hand—and I believe the same 
applies to Chimzera, of which I have no specimen—the male has 
two pairs of organs, which may be called respectively the ante- 
tior and the posterior claspers. The posterior claspers are evi- 
dently homologous with the claspers of the Elasmobranchs : they 
occur in the same position, have the form of a plate rolled longi- 
tudinally into a tube, and are supported by a prolongation of the 
basipterygium. No doubt, like the corresponding organs in 
sharks and rays, they have an intromittent function. 
The structures I call anterior claspers are situated a short 
distance cephalad of the vent, inclosed, in the position of 
repose, in a pouch of skin having a somewhat contracted slit- 
like aperture, so that the clasper is ordinarily hidden from view. 
The aperture of the sac is erroneously marked “peritoneal 
aperture” in Giinther’s figure of Chimera colliei (“* Study of 
Fishes,” p. 184). In connection with the sac is a gland secreting 
a lubricating fluid, and closely resembling the well-known gland 
of the Elasmobranch clasper. 
In the female, although the clasper itself is absent, a small 
glandular sac occurs in the corresponding position. 
The anterior clasper itself is a somewhat complicated organ, 
consisting of three chief parts supported by cartilage. The 
largest of these, which forms the main support of the whole 
structure, is a strong irregular cartilaginous plate, articulated by 
an elongated surface with the anterior border of the pubic por- 
tion of the pelvic girdle in such a way that when in its ordinary 
position of retraction, the whole apparatus is folded back in the 
hollow furnished by the outer surface of the pubic cartilage. To 
this principal cartilage of the anterior clasper are attached two 
others : one a thin delicate plate, shaped like the human external 
ear, the use of which is not obvious; the other a somewhat 
thicker plate, rolled upon itself to form a tube, in much the 
same way as the posterior clasper, and evidently serving as a 
duct for the passage of the above-mentioned secretion. ‘he 
whole apparatus is covered with soft; mucous membrane, 
NATURE 
635 
except the free portion of the principal cartilage which is 
studded with minute sharp denticles 
The clasper is exserted by the action of a strong muscle arising 
from the inner face of the pubic cartilage and passing over its 
anterior border to be inserted into the principal cartilage of the 
clasper. The plane of movement of the organ is nearly hori- 
zontal. 
That a serial homology (homoplasy) exists between the anterior 
and the posterior claspers is suggested by the following facts :— 
(a) The general similarity of their structure ; (4) they both 
articulate, mediately or immediately, with the pelvic cartilage ; 
(c) they both lie in the line of Balfour's lateral ridge, z.e. of the 
poured into a vein which is clearly the representative of the 
lateral vein of Elasmobranchii, which latter I have adduced 
reasons for considering as the vein of the proto-vertebrate lateral 
fin (Zrans. NV. Z.Inst., vol. xiii. p. 413, and vol. xv. p. 222; 
Proc. Roy. Soc., June 1886). 
I regret that all my efforts to obtain earlier embryos of Cad/or- 
Aynchus than those I described three years ago in NATURE (vol. 
xxix. p. 46) have failed. It must therefore remain for future 
investigations to decide whether the anterior clasper of Holo- 
cephali is developed from a portion of the lateral ridge which 
usually atrophies, and whether its skeleton is formed by the 
concrescence of pterygiophores (radial fin-cartilages). 
At present, therefore, the hypothesis that the anterior claspers 
of the Holocephali represent a middle pair of limbs is nothing 
more than a deduction from an unproved theory. I should not 
have ventured to publish it without further evidence if my friend 
had not, quite inadvertently, forced my hand. 
Dunedin, N.Z., August 16 T. JEFFERY PARKER 
SOCIETIES AND ACADEMIES 
SYDNEY 
Linnean Society of New South Wales, July 28.—Prof. 
W. J. Stephens, M.A., F.G.S., President, in the chair.—The 
following papers were read :—On some new or rare fishes from 
the Australian region, by E. P. Ramsay, F.R.S.E., and J. 
Douglas-Ogilby. A few notes are given on the curious Blennoid 
genus Xiphasia of Swainson, and a description is given of a 
species—NXiphasia setifer, Swainson—now for the first time taken 
in Australian waters. <Arvhamphus sclerolepis and Gastrotokeus 
biaculeatus ave recorded as fishes not previously seen on the 
New South Wales coast.—Catalogue of the Australian Coleo- 
ptera, part 5, by George Masters. The present part contains 
the large family of the Curculionidz, numbering over 1200: 
species, and bringing the total number now catalogued up to. 
5625. It was stated that probably two more parts would com- 
plete the order Coleoptera.—Miscellanea Entomologica, No. 2: 
the genus Lifarvetrus, by William Macleay, F.L.S. This is a 
complete monograph of the genus Zifaretrus. All the old 
species are redescribed, many new ones added, and the genus is 
subdivided into several sections and sub-sections. Altogether 
about 100 species are characterised.—Revision of the Australian 
Lepidoptera, No. 1, by E. Meyrick, B.A., F.E.S. Five families 
of the Macro-Lepidoptera, or Lesiadz, Arctiada, Hypside, 
Syntomidide, and Zygenide, are monographed, numbering 
about 150 species, about half that number being new to science. 
—Notes on synonymy of Australian Micro-Lepidoptera, by E. 
Meyrick, B.A., F.E.S. The synonymy of fifteen species of 
Micro-Lepidoptera is corrected, from an examination of speci- 
mens in the British Museum. 
Paris . 
Academy of Sciences, October 18.—M. Jurien de la 
Graviére, President, in the chair.—A theory of the unequal 
flow of gases, by M. Haton de la Goupillitre. Although 
geometricians have already solved a few questions relating to 
the unequal movement of fluids, no general theory appears to 
have yet been applied to the subject so far as regards the gases. 
The object of the present paper is to make good this want, and 
to present a complete solution of the problem in connec- 
tion with the receptacles ef compressed air for locomotives 
or tramways filled from reservoirs maintained by the 
compressing engines at a constant tension. — Researches 
on the tension of the dry bicarbonate of ammonia, by 
MM. Berthelot and André. The authors here discuss the 
important and complex problem, whether the tension of 
ammonia in the air, the ground, and natural waters, and its 
movements between these various mediums, is to be assimilated 
