SCIENTIFIC SEMMAEY. 
273 
found certain species of marine Entomostraca in the fresh-water lakes of 
Norway. Harpacticus chelifer was found in a lake in the neighbourhood of 
Christiansund. In the Mjoesen lake he discovered two species of Cy there, 
Mysis relicta, and Gammarus cancelloides. Jn ponds in the environs of Chris- 
tiania the Amphipod, Pontoporeia ajffinis, was discovered. These species all 
inhabit the deepest parts of the water, and live quite separate from the true 
fresh-water forms of Crustacea. The discoverer considers the presence of these 
Crustacea in the Scandinavian lakes to furnish evidence that, at the glacial 
epoch, the basin of the Baltic was in communication with either the eastern 
or western Arctic Ocean. — ^Vide Bibliotheque TJniverselle, Sept. 20, 1864 ; 
and Annals of Natural History, December. 
The Development of Baia Batis. — Some very valuable observations upon 
the development of the above-named skate have been made by Dr. J. Wyman, 
of Harvard University, U.S. He finds that (1.) the yelk case is formed in 
the glandular portion of the oviduct, and is begun previously to the detach- 
ment from the ovary of the yelk, which is to occupy it. (2.) The embryo, 
before assuming its adult form, is first eel-shaped, and then shark-shaped. 
(3.) The embryo is for a short time connected with the yelk by means of a 
slender umbilical- cord ; the cord afterwards shortens, and the young skate 
remains in contact with the yelk until the end of incubation. (4.) There are 
seven branchial fissures at first : the foremost of them is converted into the 
spiracle, which is the homologue of the Eustachian tube, and the outer ear 
canal ; the seventh is wholly closed up, and no trace remains ; the others 
remain permanently open. (5.) There are no temporary branchial fringes or 
filaments on the first and seventh arches ; on the others the fringes are deve- 
loped from the outer and convex portion of the arch, and are not at first 
prolongations of the internal gills. (6.) The nostrils, as in all vertebrate, 
consist at first of pits or indentations in the integument ; secondly, a lobe 
is developed on the minor branch of each ; and finally the two lobes become 
connected, and thus form the homologue of the fronto-nasal protuberance. 
The transitional changes of these correspond with the adult conditions of them 
in other species of Selachians. (7.) The nasal grooves correspond to the 
nasal passages of air-breathing animals, and the cartilages on either side of 
them to the maxHlary and inter-maxHlary bones. (8.) The foremost part of 
the head is formed by the extension of the facial disk forwards. While this 
extension is going on, the cerebral lobes change their position, and instead 
of being beneath the optic lobes, come iu front of their bodies. (9.) Two 
anal fins, one quite large and the other very small, are developed ; but these 
are afterwards whoUy absorbed. (10.) The dorsal fins change their position 
from the middle to the end of the tail At the time of hatching, however, 
there is still a slender terminal portion of the tail, which is afterwards either 
absorbed, or covered up by the enlarged dorsals as they extend backward. — 
Vide Memoirs of the American Academy, vol. IX. 
How the Nerves end in the Muscles of Insects. — It would appear from Dr. 
Beale’s late inquiries that the nerve filaments never penetrate the substance 
of the muscle, but are distributed as exceedingly delicate branches to that thin 
membraneous (?) portion of muscle to which the term “ sarcolemma ” has been 
given. “ Instead,” says Dr. Beale, “ of a n^rve fibre penetrating the sar- 
colemma at one point only of the muscle, and becoming connected with 
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