RECENT PROGRESS IN BIOLOGY. 667 



great interest Mr. Caldwell's account of what goes on inside these 

 eggs while the young one is growing there ; that is to say, an account 

 of the differences and resemblances between the structures which 

 gradually arise in these mammals' eggs and those which are familiar 

 to us as occurring in the case of the common fowl. 



With regard to the strange fish, Ceratodus, Mr. Caldwell has been 

 no less successful, after much disappointment and persevering search. 

 He has lately sent home a series of photographs showing groups of 

 the black men and women whom he employed to catch the fish, stand- 

 ing by the river-side and holding each one in his arms a newly capt- 

 ured specimen, while some twenty or thirty more of the fish are 

 heaped on the ground. Four years ago, zoologists were glad to buy 

 spirit-preserved specimens of this fish in London for twenty pounds 

 apiece. Mr. Caldwell has as yet sent home so few reports of his 

 doings in Australia, that every one will be interested in the following 

 letter written from New South Wales in February last : 



I shall give you a short account of my doings without apologizing for talking 

 about myself, because you asked for this. When I wrote you last I was just 

 beginning my camp-life on the Burnett River, and was very much concerned 

 about my failure in the search for Oeratodus-eggs. I had invested in an Ameri- 

 can trap and horses and all the necessaries for camping out. I remained under 

 canvas from the end of July to the end of November. Roget, my Belgian ser- 

 vant, was the only white man with me, but the blacks kept continually coming 

 and adding to the number of my retainers. I had in the end about fifty of all 

 ages men, women, and children. I have sent you some photographs which I 

 took during these months. I carried my camera everywhere, and the pictures 

 will give you a fine idea of bush scenery and the roads (?) we had to traverse. 

 I became very expert with my four-in-hand. It is a very different thing from 

 driving a team along good roads; but I was fortunate in never having a serious 

 smash. The blacks were more than useful : I could have done little or nothing 

 without them. They found over five hundred Echidna in four weeks, while the 

 "gins" searched the weeds of the river for Ceratodus-eggs. Let me tell you 

 how I found Oeratodus-spawn. From the 24th of April (1884), when I found 

 males ready to spawn, I had a pair, male and female, under constant observa- 

 tion in a small water-hole. Up to the beginning of September, though I was 

 constantly dredging and turning up the river, I got no clew to the spawning- 

 ground. I determined to give up the search for the year, as further stay on the 

 Burnett interfered with my plans for collecting the eggs of the duck -mole. All 

 August I had been getting the eggs of the duck-mole, containing very early 

 stages of the young; but with September the eggs had all been laid, and my 

 plan was to shift my camp south to the colder district of New England, where, 

 as I found in 1883, the duck-mole is a month or six weeks later in breeding. 

 One evening early in September I was shooting duck-moles as usual, when I 

 came to a place on the bank of the river where I could see several Ceratodus 

 swimming about backward and forward in shallow water. It was too dark to 

 look for anything that night, so I marked the place and described to the blacks 

 what I expected. They were down at the river by daylight, and shortly after- 

 ward returned with Ceratodus-eggs. The egg is like that of a newt, and is laid 

 in the water-weed, every egg separately. This changed my plans. I hoped 



