HISTORY OF THE SUBJECT. 23 



Dr. Joseph Leidy 1 in the same year (1847) published notes on what appears to be a small 

 freshwater Nemertean (Prostoma marginatum), but his remarks are so indefinite that they are of 

 comparatively little value. 



Prey and Leuckart next made some excellent observations, in their ' Beitrage ' (1847), on the 

 structure of the Nemerteans. 3 They described the ciliated coating, and pointed out that in these 

 animals the spike-cells (Nesselorgane) present in the Planarise were wanting. They mentioned 

 two muscular coats — an outer longitudinal and an inner circular coat, and that the nerve-trunks 

 lay on the inner side of the latter. The differences in regard to the ganglia of Tetrastemma and 

 Borlasia were shown, the authors demonstrating the shape of the organs in the former by a 

 drawing from Tetrastemma variabilis, of which, however, no additional mention is made. The 

 cephalic sacs in Borlasia {Linens) were thought to be appendages of the ganglia. They did not 

 enter into the structure of the proboscis further than to mention that it has longitudinal and 

 circular muscular fibres ; but they correctly observed that its muscular ribbons were attached to 

 the wall of its sheath, within which sheath a fluid with corpuscles existed. They did not know 

 whether the generative products escaped through the body-wall, or by rupture at the posterior 

 end, as in Arenicola ; and at any rate rupture of the body-wall might ensue for this purpose, for 

 it was not very likely that these products escaped into the body- cavity. Lastly, they compared 

 the Nemerteans with the Flukes and Trematocla. On the whole they correctly appreciated most 

 of the structures detailed by them. 



The only book of Renier's which I have been able to examine is the posthumous volume on 

 the zoology of the Adriatic, edited by Professor G. Meneghini (1847). 3 In this work the mouth 

 of the Anopla is thought to be the genital opening, and the aperture for the proboscis the 

 mouth. Little attention is paid to the proboscis, and the anatomy of the group in general is 

 much less precise than that of Delle Chiaje. The drawings, also, which accompany the text, are 

 indifferent. Six species are described, only one of which, however, appears to be British, viz., 

 Siphonenteron elegans (Renier), which Meneghini avers is identical with the Valencinia ornata of 

 De Quatrefages, and therefore with the common Carinella annulata of Montagu. 



E. Blanchard in 1S47 gives a brief but important notice of the structural position of the 

 Nermertina, Ehrenberg. 4 After having shown the principal differences between the Anevormes 

 [Bdellomorpha, Dendroccela, and Trematocla), the Cestoidea and the Plelminths, he contrasts the 

 whole with the Nemerteans. (1) In regard to the Nervous system. He considers the cephalic 

 ganglia of the Nemerteans analogous to the sub-intestinal ganglia of the other annelids ; and 

 states that their disposition quite differs from that of the Anevormes in general, and the Planarians 

 in particular. They have no closer analogy with the Nematoidea in this respect. (2) The 

 Circulatory system, he observes, presents nothing in common. (3) Digestive system. He follows 

 M. de Quatrefages in describing the digestive canal (proboscis) as simple in the Nemerteans, 

 whereas in the Planarians it is branched. (4) Generative system. He agrees with the former 

 author also in regard to his designating the Planarise and Trematoda Turbellaria monoiques, 



1 < Proceed. Acad. Nat. Sc. Philadelph./ vol. iii, 1847, pp. 251-2. 



2 "Zur Kenntniss vom Bau der Nemertinen/'' ( Beitrage zur Kenntniss Wirb. Thiere/ &c, 

 pp. 71—8 and 150, taf. i, f. 14-16. Braunschweig, 1847. 



3 ' Osservazione postume di Zoologica Adriatica del Professore Stefano Andrea Benier/ edited by 

 Prof. G. Meneghini. Venezia, 1847. 



4 ' Ann. des sc. nat./ 3eme ser., Zool., torn, viii, pp. 123—127, pi. ix_, f. 5. 



