520 Mr. G. A. Boulenger on some 



We can thus trace our rows of Ccelenterate buds along a 

 line of development, each step in which, so far as I can see, 

 would be a necessary result of their locomotory activities, 

 not as so many separate buds, but acting together as a single 

 complex organism. This line has led us, without strain or 

 difficulty, to the typical Annelid with its ccelomic cavities and 

 its parapodia. 



On page 2 I stated that I considered the metameric seg- 

 mentation so remarkable a phenomenon that wherever traces 

 of it can be discovered we are justified in assuming descent 

 from Annelidan ancestors. The segmentation found so 

 widely spread in the vegetable kingdom is a parallel pheno- 

 menon, being due to periodical buddings. In the Vertebrata 

 we have organisms which show very distinct traces of seg- 

 mentation, but complicated by the fact that their most 

 characteristic structure, the notochord, shows no traces of 

 having been primitively segmented. The jointing which 

 later appears in the vertebral column has apparently been 

 impressed upon it as a mechanical necessity by the segmented 

 organism in which it developed. For an attempt to show 

 how the vertebrate organization with its primitively unseg- 

 mented notochord can be deduced along what appears to be 

 a similarly straightforward line of mechanical adaptations 

 from an annulate ancestor, see "A new Reading in the Annu- 

 late Ancestry of the Vertebrata," Natural Science, vol. xiii. 

 1898, p. 17. 



[Note. — This paper was written eighteen months ago, and 

 was finally corrected for press before the appearance of 

 Prof. Lankester's critical resume of the subject in the recent 

 instalment of his ' Text-book of Zoology.'] 



LXIX. — On some little-known African Silurid Fishes of the 

 Subfamily Doradinse. By G. A. BOULENGER, F.R.S. 



AMONG the least-known freshwater fishes of Africa there is a 

 group of small or very small Silurids, more or less closely 

 allied to Synodontis and falling under Giinther's division 

 " Stenobranchice" which have been described in a more or less 

 satisfactory manner by various authors under the generic 

 names of Mochocus, Rhinoglanis, Ghiloglanis, Doumea, Atopo- 

 chilus, and Peltura. Having lately had the privilege of 

 examining the few specimens of these fishes preserved in the 



