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. Mybobates. 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. Ammocoetes. 



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. 



b. without teeth, Edentata. 

 Gen. Ammocoetes. 



branchialis. 



ruber, (doubtful Lac.) 



2.. Family, Hyperotreta. With the palate perforated. Myxinoidea. 



a. with connected external spiracula branchialia. 

 Myxine, ( Gastrobranchus, Bloch.) 

 glutinosa. 



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- 



