Akademie der Wissettschaften zu Berlin. 405 
of the Mammalia ; that of the Proteae and the Caeeilia, on the Amphibia ; that 
of the Cyclostomata, on the fishes ; and that of the Lernese on the Crustacea. 
The Cyclostomata are, however, doubly interesting, as they at once occupy the 
extreme limits of the fishes, and form the link between the vertebrate and in- 
vertebrate animals. So great uncertainty has hitherto prevailed with regard to 
them, that they have been placed in four different classes by naturalists, viz. 
amongst the Pisces, the Amphibia, the Mollusca, and the Vermes. The Myxine 
glutinosa was first noticed upon the coasts of Greenland and Norway by Kalm, 
and was described by him as a species of Lamprey. Linne gave it the name 
which it still bears, but classed it amongst the Vermes. Modeer placed it 
amongst the Amphibia. Retzius thought it ought to be placed in the same class 
as Petromyzon, agreeing with Linne in opposition to Camper, that it comes 
nearer to Vermes than to Pisces, and that it might without difficulty be sepa- 
rated from the latter. F. O. Miiller classed it with the Mollusca, probably on 
account of the presence of tentacula. In the edition of the Fauna Suecica by 
Retzius, the Myxine is placed amongst the Pisces. The object of the present ela- 
borate treatise is to obviate these uncertainties, and from a careful anatomical 
examination, to assign to it its true station in the animal kingdom, as well as to 
corect some errors and oversights which appear in the remarks of Bloch, Du- 
meril, Sir E. Home, and other writers upon the subject. Before proceeding to 
anatomical details, the author gives a classification of the cartilaginous fishes^ 
and particularly of the Cyclostomata, in which the Myxine is placed in confor- 
mity to its internal structure. He divides the cartilaginous fishes into four orders, 
and with regard to the sharks follows Cuvier's arrangement of the genera, 
though he thinks that, judging from the varieties found in the Mediterranean 
alone, that great naturalist has not made them sufficiently numerous. 
CHONDROPTER YGIA. Skeleton cartilaginous ; cranium without sutures. 
I. Order. BRANCHIOSTEGA* 
1. Family, CATAPHBACTA Cartilage of the cranium, and skin of the 
trunk covered at intervals with cartilaginous tubercles. 
Sturiones. Genus 1. Sturio with Brandt's subgenera, Huso, Sturio, 
Sterleta, Helops. 
2. Fam. NUDA Body without tubercles. 
Spatulariae. Genus. 2. Spatularia with the subgenera, Polyodon, Lacep. 
and Planirostra, Rafinesque, Icth. Ohiensis. 
II. Order. HOLOCEPHALA. 
Genus 1. Chimaera. 
2. CaUorynchus. 
III. Order. PLAGIOSTOMATA. 
1 . Family. SQUALL The branchial apertures riot fixed to the head. 
Genus 1. Squalus, with Cuvier's subgen. Scyllitim, Carcharias, Lamna 
Galeus, Mustelus, Notidanus, Selache, Cestracion, Spinax, Centrina, 
Scymnus. * 
2. Zygaena, Cuv. 
3. Squatina. Dum. 
4. Pristis. Lath. 
The toothless Sharks, Aodon, Lacep,, Massassa and Kumal, Forsk. are 
still doubtful. 
NO. IV. D d 
