734 REPORT — 1895. 



(swimming, di^dug, running, flying), in feeding, bathing, &c., are instinctive or 

 congenital in their definiteness ; and hnw far the definiteness of these and other 

 activities is a matter of individual acquisition. Observations were also made on 

 congenital and acquired timidity. While the perforuiance of these activities has a 

 congenital basis they are perfected by individual acquisition. There is no instinc- 

 tive and congenitalavoidance of insects with warning colours ; that appears to be 

 entirely the result of individual experience. There seems to be little or nothing in 

 the observations to afford any material support to the view that the instinctive 

 activities result from the inheritance of what is individually acquired. 



2. Notes on the Early Development of the Ganoids, Lepidosteus, Acipenser, 

 and Amia. By Bashford Dean, Instructor in BioJoyy, Columbia 

 Colleye, Neio York. 



A. Seymentationof the Eyy. — The earlier cleavages conform to the usual plan 

 of Teleost and Amphibian : — Lepidosteus and Amia meroblastic, Acipenser super- 

 ficially holoblastic. Questions as to the kinships with the yolk type of the Elas- 

 mobranch on the one hand, and with that of the Teleost on the other, were discussed. 



B. BMstnla, Gastrula. — The relations of the different forms of Ganoidean blas- 

 tula were shown in diagrams. The blastula of Lepidosteus and Shark, of Amia 

 and Teleost are similar. Comparison of Ganoidean gastrulre : the diagrams show 

 structures diverging from the type of Tiepidosteus towards that of Teleost. 



C. General Mode of the Formation of the Embryo. — Shark-like characters of 

 Lepidosteus, flattened growth of Acipenser, and Teleostean features of Amia. 



D. Conclusions. — Developmental nearnesses of Lepidosteus to the Elasmobranch 

 and of Amia to the Teleost, and the evidence on the side of embryology for con- 

 necting the line of the Teleosts with that of the Ganoids, as well as for drawing 

 more closely together the Elasmobranchian and Ganoidean phyla. 



3. On some questions relating to the Morphology and Distribution 

 of Medusa'. By Dr. Otto Maas. 



Dr. Otto Maas exhibited some plates from his monograph of the 'Albatross ' 

 Medusffi. and discussed some questions arising from the study of these Pacific forms. 

 The collection, though not very rich, is of interest in various points : 



1. Morphological. 2. Zoogeographical. 3. Bionomical. 



L Amongst 18 species 9 are new, several of them peculiar forms, for 

 Instance, a representative of the aberrant genus Homotoneme, established 1892 for 

 some forms of the ' Plankton ' Expedition. Amongst the Acraspeda we find the 

 wenera Feriphylla, Atolla, and others which are of importance for the morphology 

 of the whole group, and which have induced Clans and Vanlioffeu to a reformation 

 of Hiickd's system. The previous authors could not study the genital and sense 

 organs ; a detailed study of these shows that we can trace a line of relationship 

 from the primitive Lucernaridoe through forms like PeriphyUa and Naiiphanta to 

 the higher Discophora, forms like Atolla lying a little to the side of the line, whilst 

 Charybdea is totally away from it. The study of the canal system of the Peri- 

 phyllidse and their relations shows some primitive features in correspondence with 

 the embryology of the higher forms, i.e., the interruption of the continuous ento- 

 dermic cavity at four interradial points by the invagination of the ' Trichterhohlen.' 



2. The Medusae have been caught in an oceanic basin hitherto scarcely ex- 

 plored. In a map of the distribution of the Cathammata given by Vanholfen the 

 part of the Pacific navigated by the ' Albatross ' is an empty gap which is now 

 tilled up. 



The list of Acraspeda species shows a striking resemblance to that of the 

 ' Challenger ' Expedition. The so-called ' deep sea Medusas ' seem to have a very 



