144 THE AMERICAN MONTHLY [August, 



REPORTS OF RECENT ARTICLES. 



On the possibly dual origin of the Mammalia. — Prof. St. George 

 Mivart,* remarking on the recent discovery, by Mr. Edward Poulton, of non- 

 functional teeth in the jaws of young ornithorynchus, sa3's that, taken in con- 

 nection with Caldwell's discovery of oviporous reproduction, it greatly 

 strengthens the evidence previously relied on by certain naturalists, that the 

 ornithodelphia descended from some reptilian form. These teeth found by 

 Mr. Poulton, however, are distinctly mammalian and have no parallel among 

 the reptiles, and yet are not closely like the teeth of any other mammal. He 

 then seeks the ancestry of the monotremes, and in view of Gegenbaur's dis- 

 coveries, that their mammary glands are wholly unlike in origin to those of 

 marsupials and placentals, mammals being modified sweat glands, while in 

 the other mammals they are sebaceous follicles, he urges for them an origin 

 ' from a radically distinct stock from that from whence all other mammals 

 proceeded.' ' The monotremes are an example of hypothetical higher ani- 

 mals in the making, the future evolution of which may probably be hindered 

 by man's presence, but which, did they appear, would produce mammalian 

 forms more or less parallel to, but, of course, radically different from the 

 placental and marsupial series of mammals. 'f He assigns to them a com- 

 paratively recent origin fiom the reptilian line much posterior to the date of 

 inception of the ' superior mammalia.' 



o 



Pineal Eye in Lacertilia. — W. B. Spencer J concludes that : — i. Our 

 present knowledge is not great enough to allow us in Amphiurus to homolo- 

 gize any structure, either with the tunicate azygos eye or with the epiphysis. 



2. The epiphysis of higher chordata is the homologue of the tunicate eye. 



3. The pineal eye is produced as a secondary diflerentiation of the distal 

 part of the epiphysis. 4. There is not sufficient evidence to prove or disprove 

 the existence of the organ within the group pisces ; it was present in extinct 

 amphibia and is found amongst living forms only in lacertilia. 5. In all forms at 

 present existing it is in a rudimentary state, and, though its structui'e is better 

 developed in some than in others, it is perfectly functional in none. 6. It 

 was pi-esent and most highly developed in, (i) extinct amphibia; (2) Ich- 

 thyosaurs, Pleseiosaurs and Iguanodon, etc., ancestors of present reptiles. 

 7. Pineal eye may be most rightly considered as peculiarly a sense organ of 

 pretertiary periods. 



o 



Phosphorescence, Organ of. — J. T. Cunningham and Rupert Valentin § 

 find that in NyctipJiancs^ a crustacean allied to the shrimp-like Mysis^ organs 

 formerly described as accessory eyes, and situated as follows : — one pair be- 

 hind the eyes, two other pairs on the trunk, and four more on the median line 

 of the tail, are organs giving rise to the phosphorescence produced by the 

 shrimp, and investigate the organs thoroughly for the first time. Each organ 

 is a low mound on the surface with a transparent ' cornea,' and beneath it a 

 'lens.' The organ is globular, and its curved hind-side is composed of a 

 -concave ' reflector ' or pad of connective tissue ; between the reflector and the 

 lens the space is filled with columnar cells. Experiments with the creature 

 seem to prove that the power of emitting phosphorescence is under control 

 of the nervous system because bright flashes can be caused in response to 



*Proc. Roy. Soc, vol. xliii, p. 372, 1888. 



•j- This view of the relation of the monotremes as at once mammals and not mammals is peculiar and unsatisfac- 

 tory. We have only room to mention it here without discussion. 

 t Quart. Journ. Mic. Sci., 1887, p. 232. 

 § Quart. Journ. Mic. Sci., 1888, p. 320. 



