Ahademie der Jfissenschaften zu Berlin. 407 



mata are found at the Cape of Good Hope, in the South seas, on the coasts of 

 New Zealand, and of Chili Many of the other Cyclostomata have a still wider 

 range, as well as the peculiarity of inhabiting both fresh and salt water, as the 

 Ammoccetes, Petromyzon fluviatilis, and P. planeri, which occur in the rivers of 

 Europe ; the P. raarinus, which abounds in all the European seas, has also been 

 taken in fresh water. They have been found in Japan, Tranquebar, and South 

 America. Before he proceeds to the anatomical details, the author gives a ge- 

 neral description of the genera Myxine and Bdellostoma, which it is unneces- 

 sary to insert. The species belonging to the latter genus are furnished with 

 eyes. The Myxine glutinosa, on the contrary, is totally blind, and forms the 

 only example hitherto known of a vertebrate animal, not possessed of any visual 

 organs. Those animals which are generally called blind are always provided 

 with organs which, at least, enable them to distinguish the light, though the eye 

 itself is covered by a membrane, as Spalax typhlus, Proteus anguinus, Silurus 

 caecutiens, Acontias creciis, &c. There are many examples amongst the inverte- 

 brata of total blindness, even amongst classes, the generality of which possess 

 the power of vision. Then follows a most accurate description of the osteology 

 of the Myxinoidea, succeeded by a close comparison of their different organs, 

 with the corresponding parts in the cartilaginous, as well as other fishes, and 

 the results of a chemical examination of the bones of each. On exposing a por- 

 tion of the spinal column of the Squalus Cornubicus to a white heat till all the 

 animal matter was consumed there remained in one instance 41,55 , in ano- 

 ther, 42,068g, of ashes. These contained a very large proportion of phosphate 

 of lime, a portion of sulphate of lime, and evident traces of fluoric acid. Car- 

 bonic acid could also be detected. The cartilage of this class of fishes he di- 

 vides, according to its internal structure, into four classes. The first is called 

 the hyaline cartilage, and is nearly transparent. It is not found in Petro- 

 myzon, but abounds in the sturgeons and chimaerse. The second is the tu- 

 bercular calcareous cartilage, and is most abundant in the Plagiostomata. The 

 third is the cellular cartilage, which is found in the Bdellostomata, and the 

 fourth is termed the ossified cartilage, forming the hardest bones of many of the 

 sharks and rays. On calcining the tubercular cartilage of a large ray, there re- 

 mained an inconsiderable residuum, which consisted chiefly of phosphate of lime. 

 Fluoric acid was also perceptible, as well as carbonic acid, and sulphur ; but it 

 appeared doubtful whether the latter was in the metallic form or as sulphuric acid. 

 A portion of hyaline cartilage, carefully prepared, left a very trifling residuum, 

 which also gave evidence of containing sulphur and phosphorus, combined with 

 lime, but not so as to be separable. An analysis of the bones and cartilage of 

 Squalus peregrinus, conducted by Chevreul, and apparently with greater accuracy 

 than those made by the author, is also given. * We have not room for the de- 

 tails which follow of the comparison between the chorda dorsalis of the Cyclos- 

 tomata, and that of the higher vertebrata ; but the conclusion the author arrives 

 at is, that the spinal column of the Cyclostomata retains the same form and 

 condition as that which we find in the embryos of the higher orders of animals, 

 during the first days of their conception. The following are the gradations 

 which the spinal column undergoes in its structure, ascending from the lower 

 to the higher animals. 



* Vide Ann. du Musee d'Hist. Nat. Tom. xviii. 



