HISTORY OF THE SUBJECT. 35 



minute details of the classification, since it appears to be little else than a confused grouping. 

 In the first place, it has not yet been proved that these furrows and fissures are branchial ; 

 secondly, the locating in the family Rolocephala genera so widely divergent as Falencinia, 

 De Quatrefages, and Ommatoplea, Ehrenberg, the arranging under two different sub-orders of 

 the closely allied forms (Erstedia and Tetrastemma, and the statement that in Micrura the 

 head is furnished with a single terminal transverse fissure, are certainly sufficient to shake our 

 faith in the author's knowledge of the subject. 



An interesting contribution to the anatomy and zoology of the Turbellaria was published 

 by M. van Beneden in I860, 1 the Nemerteans occupying the first part of the memoir. He 

 correctly observed the apertures of the generative organs along the sides, but erroneously con- 

 sidered that the proboscis floated in the general cavity of the body. He had good reasons for 

 supposing that the coat of the digestive tract combined the functions of the liver as well as an 

 alimentary organ proper. His anatomy of the cephalic sacs in the Anopla was inaccurate. He 

 discovered that some of the embryos in Nemertes communis were ciliated in the ova before laying ; 

 and his observations on the development of Folia involuta {Nemertes carcinophila, Kolliker), form 

 the most valuable portion of the memoir, though he was wrong in supposing that one form was 

 evolved out of the other, like a scolew engendering a proglottis. He also made the mistake of 

 placing the mouth of the Enopla (ex. Folia obscura) behind the ganglia, instead of in front of 

 them. His memoir is illustrated by four lithographic plates, some of the figures being coloured. 



E. Claparede, in his remarks on Tetrastemma varicolor, (Erst., and another from Skye, 3 in 

 1861, clearly pointed out the duct to the marginal stylet-sacs. He considered the latter to 

 be the receptacles for stylets rejected from the central apparatus, and he combated the contrary 

 view held by Max Schultze. While he observed the cavity of the reservoir, he fell into the 

 error of calling the posterior chamber the muscular retractor of the organ. He also notes the 

 form of the papillae in the proboscis of Ceplialothrix lineala. 



In 1862 Diesing produced a 'Revision' of the Turbellaria? the Nemerteans being placed 

 under the second Tribe Bhynchoccela, some of them occurring after the Families Bhynchoscolecidea 

 and Gyratricina in his sub-tribe Bhynchoccela Aporocephala, and the rest under a second sub- 

 tribe B. Porocephala. The former contains the families Borlasiea, Ommatophora, Micrurea, 

 Hypoloba, and Acroloba ; the latter Prorhynchidcs, Emeidea, Typklonemer tinea, Loxorrhocltmidea 

 and JEunemertinea. The confusion and errors in this brochure are not fewer than in the preceding, 

 and render it almost beyond the pale of criticism. 



The most important and at the same time the most recent publication of note on the 

 Nemerteans is that of Professor Keferstein, from observations made at St. Vaast-la-Hougue. 4 It 

 will be necessary to enter somewhat minutely into this contribution, which marks another era 

 in Nemertean literature. He first treats of their classification as follows :— 



1 'Recherches sur la Faune Littorale de Belgique/ extrait du tome xxxii des ' Memoires de 

 PAcademie Royale des Sciences de Belgique/ 1860. 



2 f Recherches Anat. sur les Anelides, Turbellaries, &c, observes dans les Hebrides/ Geneve, 1861. 



3 " Revision der Turbellarien, Abtheilung Rhabdocoelen." < Sitzungsb. d. Kais. Akad. d. wissensch. 

 Wien./ 1862, pp. 199—204 and 247—306. 



4 ' Zeitsch. fur wiss. Zool./ Bd. xii ; pp. 51—90, taf. 5—7, 1862. 



