HISTORY OF THE SUBJECT. 31 



Linens marinus, that he was not aware the animal had a proboscis, for he distinctly refers to 

 this organ in other species. He also correctly observed the true mouth in the Anopla, since 

 he saw the animals feeding, and recorded many interesting facts with regard to the deposition 

 of ova. The great Gordius fragilis has not been procured since he found it, so far as can be 

 ascertained. The figures in this work are executed with care, and most are coloured. R. 

 Leuckart, in his abstract of the literature of the Turbellaria for 1858 * furnishes the synonyms of 

 the majority of the species described by this author. 



In the same year (1853) Charles Girard gives descriptions of some new Nemerteans from 

 the coasts of the Carolinas, for which he establishes several genera. 2 He interprets the true 

 mouth in the Anopla as the aperture of the generative system, while he terms the proboscidian 

 aperture the mouth. The description of his Stimpsonia, as it appears in this paper, differs from 

 Bipalium in several important particulars. 



Dr. Thomas Williams 3 likewise published, in 1853, an account of the method of aquatic 

 respiration in invertebrate animals, and specially refers to the " Nemertidse " as having the whole of 

 the digestive chamber filled with a corpuscular fluid, which, he states, carries out this important 

 function. He shows a drawing of the alimentary system of a species named Nemertes Camilla, 

 which may be synonymous either with N. gracilis or N. Neesii, probably the former. He still 

 erroneously places the anus towards the anterior end, and avers that the organization of the 

 "Nemertine Annelida" conforms in every essential particular to that of the Cestoid Entozoa. 



Next year C. Gegenbaur 4 mentions that he frequently found Pglidium gyrans at Messina, and 

 gives remarks on its structure. From his description it would appear that he found the Nemertean 

 Pylidium, but did not quite interpret its full relationship. He noticed that it differed from the 

 'EchmodeTm-Pylidium, and at first thought that the whitish oval body in its interior had been 

 swallowed, but the occurrence of others of the same species convinced him of the connection 

 between the two. 



In his 'Archiv 'for 1854 J. Miiller adds still further to our information on the develop- 

 ment of the Nemertean Pylidium} He recognises the identity of the contained body with the 

 Alardus caudatus of Dr. Busch, and gives a somewhat better figure of the worm, with a normal 

 arrangement of the caudal process ; and his remarks on its structure are likewise more correct. 

 He mentions the fact that Micrura fasciolata, Ehrenberg, has a terminal process, but does not 

 state the identity of the two, since his young form possesses only two eyes, whereas the former 

 has ten. In this paper he also notes certain experiments with hot water which he performed 

 on Meckelia somatotomus, Leuckart. 



Dr. E. Grube, 6 in his introductory remarks on the Nemerteans (in 1855), criticises the 

 interpretations of the proboscis adopted by M. de Quatrefages, and points out that the true digestive 

 apparatus Kes below the former, each system opening by a definite aperture in the snout of the 

 Anopla, He thought it probable that the Nemerteans used the proboscis after the manner of 



1 ( Archiv fur Naturges./ 1859, pp. 187 and 188. 



2 ' Proceed. Acad. Nat. Sc. Philadelphia/ vol. vi, 1853, pp. 365-367. 



3 f Ann. Nat. Hist./ 2nd ser., vol. xii, pp. 341, &c, plate xiii, figs. 1 and 2. 



4 'Zeitsch. fur wiss. Zool./ Bd. v, 1854, p. 345. 



5 f Archiv fur Anat./ 1854, pp. 75—84, taf. 4, f. 2—8. 



6 "Bemerkungen iiber einige Helminthen u. Meerwiirmer/' < Archiv fur Naturges./ 1855, pp 

 145—152, taf. 7, f. 1—4. P ' 



