Prof. E. Claparede on the Structure of the Annelida. 339 



order Nereidea) has appeared^ has nothing general except its 

 title. It contains in reality a series of monographs devoted to 

 certain species found in the Adriatic. These monographs are 

 combined into a sort of whole by taxonomic considerations. 

 There is nothing deserving the name of a ' Treatise on Annelida ;' 

 the number of types investigated by the author is too small for 

 this. Nevertheless M. Ehlers's monographs are models of 

 exactitude. Whenever I have had the opportunity of repeating 

 the observations of this anatomist, T have been obliged to admit 

 their perfect truthfulness, even in details of secondary import- 

 ance. 



The 'Histoire Naturelle des Anneles' of M. de Quatrefages 

 corresponds better with its title. It is a real treatise on the 

 Annelida Polychseta. The author has set before him two ob- 

 jects : — in the first place, a natural classification founded on ana- 

 tomy ; and then an enumeration of all names and synonyms, in 

 order to enable any one to find more easily the numerous me- 

 moirs and passages relating to Annelida which are now-a-days 

 disseminated pretty nearly everywhere. The author has devoted 

 long-continued attention and assiduous and prolonged labour 

 to this rather dry work, the fruits of which will chiefly be 

 gathered by others. No doubt this immense compilation pre- 

 sents some gaps or omissions, several of which will be indicated 

 in the present memoir ; but it could hardly have been otherwise, 

 considering the labyrinth through which the author had to find 

 his way. The clue which the ' Histoire des Anneles ' places in our 

 hands will be henceforward a guide which cannot be disdained. 

 This guide, indeed, must not be employed without a check. 

 The author has often consulted plates without taking the trouble 

 to read the corresponding text. The imperfection of a figure, 

 or a slip of the graver, has often led him into serious mistakes. 

 Thus, in his family Nerinea, M. de Quatrefages characterizes the 

 worms of the genus Pygospio (Clap.) by the sole circumstance 

 of their having uniramous feet, in opposition to all the rest of 

 the family, in which the feet are biramous *. It is only neces- 

 sary to open the volume in which I established the genus Py- 

 ffospio t to see that I indicate the feet as biramous, and that I 

 describe in detail each ramus and the setse which it bears. M. 

 de Quatrefages, neglecting to read the text, has, no doubt esta- 

 blished his false diagnosis from a figure on a small scale which 

 accompanies my memoir, in which the dorsal ramus covers the 

 ventral one, and scarcely allows it to be seen. The following is 

 another perfectly similar example. Under the name of Lumbri- 



* Hist. Nat. des Anneles, tome i. p. 437. 



t Beobacht. iiber Anat. und Entw. wirbelloser Tbiere an der Kiiste der 

 Normandie angestellt. Leipzig, I8ti3, p. 3/. 



23* 



