ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 409 



de l'Astrolabe ' (pi. xxviii. fig. 2), and to some other cases, where 

 peculiar markings on the skin have been described. These, as Captain 

 Chaves suggested, are almost certainly the scars left by the suckers of 

 ArcMteuthis and other cuttlefishes. 



Tracheal Bulb in Male Anatidae.* — Frank Finn contributes some 

 interesting notes on the structure and function of the peculiar bony, or 

 bony and membranous, bulbs found at the base of the trachea in many 

 males of the duck tribe. There can be no doubt, from the observations 

 made, that the use of this peculiar structure is to rnodifv the voice of 

 the owner, as Yarrell suggested. Careful st idy of the living birds will 

 show that in nearly every case where the tracheal enlargement exists in 

 the male, he emits a correspondingly different note from the female — 

 generally one of a weaker character, if not always. A table of nine 

 instances is given, bearing out this conclusion. 



Position of Dipnoi.f — Dr. R. Semon briefly summarises the various 

 views which have been held on this subject, and gives as his own opinion 

 that the Dipnoi are more nearly related to the extinct group of fish from 

 which Amphibia originated than any class of fishes of which we have 

 living representatives. As to the suggestion that the resemblances 

 between Amphibia and Dipnoi may be due to convergence, produced by 

 the habit in both cases of alternating between an aquatic and a terrestrial 

 life, the author notes that the terrestrial habit is wholly exceptional in 

 the Dipnoi, that they cannot take food on land, and have limbs not 

 adapted for terrestrial progression. Further, under these circumstances, 

 the suggestion of parallelism in development could only explain the 

 structure of organs directly associated with the air-breathing habit, 

 (lungs, posterior nares, heart, circulatory organs) or influenced by the 

 absence of water (skin and peripheral sense-organs), but it is not only 

 by such organs that a relationship with Amphibians is shown. Thus, 

 although the fins are not used in terrestrial progression, they possess a 

 stylopodium free from fin-rays (homologue of humerus and femur), and a 

 joint corresponding to that of elbow and knee in terrestrial forms. Again, 

 the brain shows the beginning of commissures in the hemispheres, a lobus 

 hippocampi, ganglion-cells in the central grey matter, and two cortical 

 layers ; the ductus endolymphaticus exhibits a complicated structure ; 

 the cranial nerves show many deviations from the fish-type, deviations 

 of a kind which reappear in Amphibia ; the post-branchial body is rudi- 

 mentary ; the tissue elements agree with those of Amphibia ; many of 

 the details of development recall the conditions in Amphibia — all 

 characters which cannot be explained away as due to convergence. On 

 the other hand the Crossopterygia, which have been frequently described 

 as the fish most nearly related to Amphibia, possess only such Amphibian 

 characters as are shared by the Dipnoi, to whom the Crossopterygia are 

 undoubtedly related. The author further considers that, while the 

 Crossopterygia lack the progressive Amphibian-like characters of the 

 Dipnoi, they are along their own lines as specialised as the latter. As 

 to the nature of the relation between Amphibia and Dipnoi, the author 

 inclines to the view that they are offshoots of a common stem, but he 



* Journ. Asiatic Soc. Bengal., lxix. (1900) pp. 147-9. 

 t Zool. Anzeig., xxiv. (1901) pp. 180-8. 



