1844-1858] ABERRANT GENERA 83 



genera would have only 4*91 species on an average. I tested Letter 41 

 these results in another way. I found in Schoenherr 9 

 families, including only 1 1 genera, and these genera (9 of 

 which were in Waterhouse's list) I found included only 3 '36 

 species on an average. 



This last result led me to Lindley's Vegetable Kingdom, in 

 which I found (excluding thallogens and acrogens) that the 

 genera include each io - 46 species (how near by chance to 

 the Curculionidae), and I find 21 orders including single 

 genera, and these 21 genera have on average 7^95 species ; 

 but if Lindley is right that Erythroxylon (with its 75 species) 

 ought to be amongst the Malpighiads, then the average would 

 be only 4'6 per genus. 



But here comes, as it appears to me, an odd thing (I hope 

 I shall not quite weary you out). There are 29 other orders, 

 each with 2 genera, and these 58 genera have on an average 

 15^07 species : this great number being owing to the 10 genera 

 in the Smilaceae, Salicaceas (with 220 species), Begoniaceae, 

 Balsaminacese, Grossulariaceae, without which the remaining 

 48 genera would have on an average only 5 '91 species. 



This case of the orders with only 2 genera, the genera 

 notwithstanding having 15*07 species each, seems to me very 

 perplexing and upsets, almost, the conclusion deducible from 

 the orders with single genera. 



I have gone higher, and tested the alliances with I, 2, and 

 3 orders ; and in these cases I find both the genera few in 

 each alliance, and the species, less than the average of the 

 whole kingdom, in each genus. 



All this has amused me, but I daresay you will have a 

 good sneer at me, and tell me to stick to my barnacles. By 

 the way, you agree with me that sometimes one gets despond- 

 ent for instance, when theory and facts will not harmonise ; 

 but what appears to me even worse, and makes me despair, 

 is, when I see from the same great class of facts, men like 

 Barrande deduce conclusions, such as his Colonies 1 and his 



1 Lyell briefly refers to Barrande's Bohemian work in a letter (August 

 3 ist, 1856) to Fleming (Life of Sir Charles Lyell, II., p. 225): "He 

 explained to me on the spot his remarkable discovery of a ' colony ' of 

 Upper Silurian fossils, 3,400 feet deep, in the midst of the Lower Silurian 

 group. This has made a great noise, but I think I can explain away the 

 supposed anomaly by, etc." (See Letter 40, Note I,) 



