The paper on fish development was mainly based upon dissections of the young of the stickleback. Fishes had been divided into two classes according as their tails are developed evenly on either side of the line of the spine, which was supposed to continue straight through the centre of the tail, or lopsided, with one tail fin larger than the other. This investigation showed that the apparently even development was only an extreme case of lopsidedness, the continuation of the "chorda," which gives rise to the spine, being at the top of the upper fin, and both fins being developed on the same side of it. Lopsidedness as such, therefore, was not to be regarded as an embryological character in ancient fishes; what might be regarded as such was the absence of a bony sheath to the end of the "chorda" found in the more developed fishes. Further traces of this bony structure were shown to exist, among other piscine resemblances, in the Amphibia. Finally the embryological facts now observed in the development of the bones of the skull were of great importance,] "as they enable us to understand, on the one hand, the different modifications of the palato-suspensorial apparatus in fishes, and on the other hand the relations of the components of this apparatus to the corresponding parts in other Vertebrata," [fishes, reptiles, and mammals presenting a well-marked series of gradations in respect to this point. This part of the paper had grown out of the investigations begun for the essay on the Vertebrate Skull, just as that on Jacare and Caiman from inquiry into the scales of Stagonolepis. Thus he was still able to devote most of his time to original research. But though in his letter of March 27, 1855, below, he says,] "I never write for the Reviews now, as original work is much more to my taste," [it appears from jottings in his 1859 notebook, such as "Whewell's 'History of Scientific Ideas,' as a Peg on which to hang Cuvier article," [that he again found it necessary to supplement his income by writing. He was still examiner at London University, and delivered six lectures on Animal Motion at the London Institution and another at Warwick. This lecture he had offered to give at the Warwick Museum as some recognition of the willing help he had received from the assistants when he came down to examine certain fossils there. On the way he visited Rolleston at Oxford. The knowledge of Oxford life gained from this and a later visit led him to write:--] The more I see of the place the more glad I am that I elected to stay in London. I see much to admire and like; but I am more and more convinced that it would not suit me as a residence. [Two more important points remain to be mentioned among the occupations of the year. In January Huxley was elected Secretary of the Geological Society, and with this office began a form of administrative work in the scientific world which ceased only with his resignation of the Presidency of the Royal Society in 1885.