HISTORY OF THE SUBJECT. 25 



In a subsequent paper in the e Annates' for 1849/ M. Blanchard adopts the general 

 anatomy of the Nemerteans given by M. de Quatrefages, and agrees with the latter in thinking 

 that the affinities of the group lie rather with the Helminths than the Planarians, on account of 

 the erroneous view with regard to the csecal nature of the digestive tract. Moreover, in all the 

 known Aporocephales (Planarians) the sexes are united in one individual, whereas in the 

 Nemerteans they are separate. The latter likewise have a veritable oesophageal collar, which is 

 wanting in the former. He proposes the name Ajploccela as distinctive of the characters of the 

 group (the simplicity of their intestine), and thinks that the title Nemerteans should be 

 applied only to a tribe or family. No fresh observations are produced in this paper, and the errors 

 in regard to the digestive system are rendered more conspicuous. 



M. cle Quatrefages at this time published his valuable and extensive observations, begun at 

 the lies Chauseg in 1841, and carried on subsequently at St. Malo, St. Vaast-la-Hougue, Brehat, 

 Sicily, &c, on the anatomy and zoology of the order, with additional coloured plates, in the 

 second volume of the c Voyage en Sicilie/ the joint work of Milne Edwards, Blanchard, and 

 himself. 3 The author, after giving an account of the history of the group, proceeds to treat of 

 their characteristics and classification thus : — ■ 



Nemertians. — Nervous system distinct, composed of two lateral lobes united above by a 

 slender commissure, beneath by a broad sub-cesophageal commissure, and giving origin to 

 two isolated longitudinal nervous trunks. Circulatory system shut; circulation complete. 

 Alimentary tube simple ; proboscis exsertile ; intestine csecal. Sexes separate ; reproductive 

 organs placed at the sides of the abdominal cavity, and occurring throughout the entire length of 

 the body. Surface quite smooth, covered with vibratile cilia. He distinguishes his six genera 

 as follows : 



NEMERTIANS 



Nerve-trunks entirely- 

 lateral in position 



f Month subterminal, inferior Valeneinia. 



f Very flat .... Borlasia. 

 Body very long ~{ 



l^ More or less rounded Nemertes. 

 Mouth terminal < 



C Very proteiform . . Polia. 

 __ Body short -{ 



(^ Form less variable . Cerebratulus. 



Nerve-trunks sublateral (Erstedia. 



This arrangement, from the inaccuracy and limited extent of his observations in regard to 

 the position of the nerve-trunks in the various groups, is useless ; and the subordination into 

 genera rests upon an equally unreliable basis. Not a few in his list of thirty-two species are 

 forms previously known, though described as new worms — several more than once ; and it is to be 

 remarked that some of the very common specimens, e.g. Lineus gesserensis and L. sanguineus, are 

 not mentioned, or else are so described as to be unrecognisable. 



He characterises the animals as chiefly nocturnal in their habits, with the exception of Polia 



1 "Recherches sur T organisation des Vers/' 'Ann. des sc. nat./ 3me ser., Zool., torn, xii, 

 pp. 28—35. 



2 f Recherches Anatomiques et Zoologiques faites pendant un Voyage sur les cotes de la Sicilie et 

 sur les divers points du littoral de la France/ par MM. H. Milne Edwards, A. de Quatrefages, et 

 Emile Blanchard ; deuxieme partie, pp. 85—220 ; pis. ix— xxiv, par A. de Quatrefages. Paris, 1849. 



4 



