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



mination of the figures of my illustrious predecessor, that these 

 facts were perfectly familiar to him*. Thus in every page, in 

 the course of this memoir, I shall have to bring Delle Chiaje out 

 of the undeserved obscu^rity in which he has too often remained 

 immersed, and to show him shining in the first rank. I hope 

 I shall not be accused of partiality in his favour. If 1 often 

 leave his errors, which I admit are numerous, in oblivion, it is 

 because they have no influence on the |jrogress of science. 



The circumstances under which I undertook the present 

 researches were eminently favourable. Science had just been 

 enriched by two important works relating to the Annelida — one 

 by M. Ehlers, the other by M. Quatrefages. Both of them pro- 

 fessed more or less to represent the actual condition of our know- 

 ledge. Aided by this double compendium, I could advance with 

 much more certainty upon a road which had been rendered easy. 



I do not conceal from myself how much 1 am indebted to the 

 authors of these works for trouble avoided, for facilitated inves- 

 tigation f, for the sapping of errors even before their birth. 

 Nevertheless, without injustice towards them, I may be allowed 

 to say that the compendium has not always performed what it 

 seemed to promise. 



The work of M. Ehlers, of which only one part (including the 



* At the moment I shall only cite an examjile taken from beyond the 

 limits of the subject with which I am at present occupied. A fine Dendro- 

 cele Turbellarian, Thysanozoon tuberculatum {Planaria tuberculata, Delle 

 Chiaje, Thysanozoon DiesinriU, Grube) is found in abundance in the Bay 

 of Naples. In studyin^j; this animal, I was struck by various anatomical 

 peculiarities, but esjjccially by the following one : — The male apparatus is 

 formed of two perfectly distinct halves. There exist two penises opening 

 outwards, each separately, in the anterior part of the body, in front of the 

 female pore. Dendroccela were already known with a single sexual orifice, 

 and others with two ; but here was one with three apertures. This exce])- 

 tional fact naturally struck me. But what was my surprise, on turning 

 over the works of Delle Chiaje, to find a figure, without explanation, with- 

 out text, without even a name at the bottom of the page, representing 

 beyond any doubt a ])ortiou of the ventral surface of T. tuberculatum, and 

 indicating very exactly the three sexual pores (see Descr. e Notomia degli 

 Animali senza Vertebre, tab. 109. fig. 19. The male pores bear the letter 

 d, and the female pore the letter r). This figure has slumbered since the 

 year 1841, unknown to anybody. Delle Chiaje has inscribed at the head 

 of one of his works the motto " Res non verba." He has been faithful to 

 it, perhaps even too faithful. 



t In coimexion with this, however, it is impossible for me not to point 

 out a defect in the work of M. Quatrefages, which, no doubt, is not to be 

 ascribed to its author. I mean the number of false citations. The quan- 

 tity of typographical errors in the indication of volumes, pages, plates, and 

 figures exceeds anything that could be imagined, and deprives the work of 

 one of the merits which ought to have led to its most frecjuent consulta- 

 tion. Nowhere would exactitude have been more <lesirable than in this 

 sort of dictionarv of science. 



