1899] DEVELOPMENT OF LEPLDOSLREN 433 



immediately above the fore limb. After the close of the larval period 

 the Lepidosircn becomes much darker in colour and more lively in its 

 movement. Young were obtained from the nest up to a length r of 

 GO mm. About this time the cornea begins to assume the white 

 unhealthy appearance that it has in the adult. In the young of this 

 size small yellow spots appear, and in the young of 90 mm. these are 

 conspicuous. Occasional yellow blotches persist in the young Lepido- 

 sircn of eighteen months, but in the adult they disappear. 



The segmentation approaches most closely that of Ganoids. The 

 shortening up of the invaginating groove is considered to illustrate a 

 process which has taken place in phylogeny in the passage from the 

 primitive holoblastic egg to the meroblastic condition. The continuity 

 of the medullary folds behind the anus is adduced, together with the 

 evidence of the prolongation of the blastopore along the floor of the 

 medullary groove in other forms (Amphibia, Ceratodus), as affording 

 potent evidence in favour of the hypothesis which derives the Verte- 

 brata from ancestral forms as primitive as the Coelentera, and possess- 

 ing an elongated mouth traversing the neural surface. The occurrence 

 of external gills in the young of three so comparatively primitive groups 

 of Vertebrata as Crossopterygians, Dipnoans, and Amphibians, their 

 occurrence on four branchial arches in Lepidosiren, and on at least the 

 hyoid arch in Crossopterygians, and the occurrence of a probable homo- 

 logue on the mandibular arch in Urodela, are taken as suggesting that 

 these structures are organs of great antiquity in the Vertebrate stock, 

 and that there was formerly one present on each visceral arch. It is 

 pointed out that were this so, it would afford a theory of the origin of 

 vertebrate limb, which would be supported by much of the evidence 

 brought forward by the supporters of Gegenbaur's view, and which at 

 the same time would avoid the most important difficulties in the way 

 of this theory. 



The Man in the Beast. 



Compakative psychology is the most anarchic department within the 

 naturalist's province. The reasons for this are twofold. On the one 

 hand, the subject-matter is in great part within the reach of all, and 

 amateurs — most delightful people as long as they retain some sense of 

 their limitations — rush in with inaccurate observations and incompetent 

 inferences. On the other hand, the problems are intrinsically very 

 difficult, so that it is at present hardly possible for the most careful 

 experts to formulate even a small number of certainties to question 

 which might be ruled irrelevant. Moreover, there are various vested 

 emotional and other interests which are believed to be more imperilled 

 by opinions regarding instinct than by those regarding protoplasm. 

 All this being so, we are not assuming any position of superiority 



