ON THE BRITISH ANNELIDA. 239 



■wall) seul fait mention a M. Dumeril, qui I'a trouve pres de Brest. M. Oken 

 en fait son genre Borlasia, M. Sowerby I'avait nomme Lineus." 



In the preceding definition Cuvier commits himself to several important 

 points of structure, the incorrectness of which, it will be subsequently shown, 

 may now be proved by easy and direct demonstration. It is first stated that 

 the body in these worms terminates in a blunt point perforated by an anal 

 orifice. This is an unquestionable error. The posterior extremity of the 

 body in all the species of this genus is imperforate. It is next affirmed that 

 the intestine traverses the whole length of the body, and that " another canal, 

 probably concerned in generation, winds along the sides, and terminates by 

 a tubercle on the side, by a large orifice." The constituent elements of struc- 

 ture have thus been accurately recognised by Cuvier, but very erroneously 

 interpreted. It will be hereafter demonstrated that " the second canal," ter- 

 minating at the side, is concerned in digestion, not in generation. It is a 

 compound of oesophagus and proboscis. The figures by M. Quatrefages of 

 Nemertes Borlasii represent this worm as possessing several longitudinal 

 fissural oral orifices adapted for sucking. Nor does it appear that this saga- 

 cious naturalist had become at all acquainted with the existence in this 

 remarkable Annelid o^ a proboscis. His conception, therefore, of the mecha- 

 nism by which it obtains food must have been remote from the truth, since 

 the oral end of the alimentary system is not many-fissured, but composed 

 only of a single longitudinal slit underneath the conical rostrum : with such 

 an orifice it is manifest that the process of suction would be impracticable. 

 In the beautiful illustrations of the anatomy of Nemertes Camilla, published 

 from the inedited researches of M. Quatrefages in Crochard's edition of the 

 ' Regne Animal,' this author describes the jaws, which are situated at the 

 extremity of the proboscis when protruded (an extraordinary organ in these 

 worms), as being contained in a pouch of the digestive cavity, " poches a 

 stylets en voie de formation." The dissections of this worm by M. Quatre^ 

 fages are, notwithstanding this instance of a misinterpretation of structural 

 characters, accurately defined, and, as far as they have extended, confirmed 

 by those of the author. It is, however, not a little surprising, that the 

 real organic characteristic of these worms should have eluded the eye of an 

 ingenious observer, who bad attained to a point bordering closely on a true 

 solution of the problem, viz. the real mechanism of the proboscis and oeso- 

 phagus. And in relation to the function of that large glandular mass which 

 constitutes so considerable a proportion of the whole bulk of the worm, 

 M. Quatrefages shares the erroneous views already propounded by Cuvier, both 

 describing it as a reproductive (ovarian) organ. 



In the year 1844? Prof. CErsted of Copenhagen published an important 

 contribution to the anatomy and systematic description of the JVemertini*. 

 The diagnostic descriptions of this observer prove beyond question that he 

 also missed the right clue to the secret of the true organization of these 

 worms ; he describes the buccal fissures as designed to admit water into con- 

 tact with the heart for the purposes of respiration. He describes the anal 

 orifice as having a terminal situation. He states that the proboscis is " nullum 

 exsertile," and, like Cuvier and Quatrefages, he falls into the error of charac- 

 terising the 'glandular organ,' which occupies nearly the whole length of the 

 body, as the reproductive apparatusf . In fact, the differences between the 



* Entwurf einer systematischen Einfcheilungund speciellen Besdirabung der Plattwiirmor, 

 Kopenhagen, 1844, p. 76. 



t By M. CErsted the Nemertini are regarded as a suborder of Vermes Apodes, and are 

 characterized as follows : — " Corpus liueare teretiusculum rarius depressum, multo longius 

 quam latius, indistincte annulatum, mucosum, ciliis vibrantibus obsitum ; musculi distincti, 



