406 Abhandlungen der Koniglichen 
2. Family, RAI^E. The branchial apertures fixed to the head. 
Gen. 5. Rhinobatus, Schn. with the subgen. Rhinobatus and Rhina, 
(the latter doubtful.) 
6. Torpedo, with the subgen. Torpedo and Narcine, Henle. 
7. Raia. Subgen. Raia, Trygon, and Anacanthus. 
8. Propterygia, Otto. 
9. Myliobates. Subgen. Myliobates, Dum. and Rhinoptera, Khul. 
10. Cephaloptera, Dum. with subgen. Cephaloptera, and one other, not 
named. 
IV. Order CYCLOSTOMATA. 
1. Family, HYPEROARTIA. With the nasal aperture closed, and the palate en- 
tirely covered with skin 
Genus. 1. Petromyzon. 
2. Ammoccetes. 
2. Family, HYPEROTRETA. With the palate perforated. 
Genus 3. Myxine. 
4. Bdellostoma, Nob. 
The author then proceeds to describe the characteristic points in his divisions 
of this fourth order of Cartilaginous fishes, (the Cyclostomata,) and the various 
new species which he has discovered. 
1. Family, CYCLOSTOMATA HYPEROARTIA. 
a. with the teeth visible, Dentata. Genus, Petromyzon. 
Species, murinus, argenteus, fluviatilis, planeri. 
6. without teeth, Edentata. 
Gen. Ammoccetes. 
branchialis. 
-ruber, (doubtful Lac.) 
2. Family, HYPEROTRETA. With the palate perforated. Myxinoidea. 
. with connected external spiracula branchialia. 
Myxine, ( Gastrobranchus, Bloch.) 
glutin osa. 
b. with separated external spiracula branchialia. 
Bdellostoma. 
Hexatrema (spec. nov. Nob.) Table bay. 
Heterotrema (spec. nov. Nob.) Table bay. 
Heptatrema Nob. South sea. 
Forsteri, Nob. (Petromyzon cirrhatus, Bloch, Forster.) 
New Zealand. 
Doubtful species. Dombeyi. 
The stability of this arrangement of the species depends upon the supposition 
that the number of the branchial openings and of the teeth upon the tongue re- 
main constant, which future observations must determine. The teeth on the 
tongue of Myxine glutinosa are very constant. The habits of the last mention- 
ed species are very little known. It is said by Kalm to attach itself to the 
body of the stock-fish, and to extract nourishment from it. By other writers 
it is said to penetrate into the intestines of different species of fish. 
The Bdellostoma Forsteri is found hanging to the fragments of fish which 
are placed in nets as bait. Forster says that it frequents rocky places, near 
the sea shore. While the Myxine frequents the Northern seas, the Bdellosto- 
