16 HISTOEY OF THE SUBJECT. 



be a freshwater Nemertean {Prostoma clepsino'ides) , which he discovered in French streams. 1 He 

 found that it differed entirely in type from the Planarians which he had been describing, since it 

 did not possess their gastric ramifications, but had a simple alimentary tube (proboscis), forming 

 several convolutions. The latter organ commenced in front by a probably exsertile mouth, and 

 terminated posteriorly in a rounded anus. 



In the same year (1828) M. de Blainville 3 placed the Nemerteans along with the Planarians 

 under the Class Bntomozoaires apodes ou Vers, in the Sub-class Parentomozoaires ou Sub-Annelid 

 daires, and in his first Order Jporocepkala. He established his first Family, Teretularia, for 

 their classification, but associated with them. Bonellia, a Gephyrean. His genera of true Nemerteans 

 were Tubulanus (Renier), Op/tiocepkalus (Quoy and Gaimard), Cerebratulus (Renier), Borlasia 

 (Oken), Lobilabrum (De Blainville), and Prostoma (Duges). He correctly described the mouth 

 in the Anopla (to which group almost all his species, with the exception of Prostoma, belonged), 

 and the general characters of the animals. His figures of Borlasia anglice in the Atlas are fair. 



Dr. G. Johnston 3 continued his observations on Planaria in 1829, describing Planaria 

 octoculata, P. quadrioculata, P. bioculata, and P. filiformis. The first mentioned refers to 

 Lineus sanguineus, the second to Tetrastemma Candida, the third to Z. gesserensis, and the fourth 

 to Cephalothrias linearis. His accounts are short, but easily recognised. 



In 1830 M. Duges published descriptions 4 of four species of Prostoma, and gave certain 

 anatomical details. One of these, however (now called P. clepsinoidemn), was mentioned in 

 the previous paper • the second, P. lumbricoideum, is probably Tetrastemma Candida ; the third, 

 P. candidum, Miiller, appears to be the same species ; and the fourth, P. armatum, has so many 

 eye-specks that, if the description is correct, it is a species with which I am unacquainted. His 

 anatomical investigations were made on the latter. He confounded the proboscis with the diges- 

 tive system, and the nervous with the circulatory system. 



Professor Huschke 5 in a notice of the anatomy of Notospermus drepanensis {Cerebratulus 

 geniculars, De Quatref.), from tufts of Corallina officinalis on the shores of Sicily, published 

 at this time, mentions that there are two muscular coats under the skin, an external longitu- 

 dinal and an inner circular; the inner longitudinal muscular coat having escaped observation. 

 He truly interpreted the alimentary canal, with its post-ganglionic mouth and terminal anus, but 

 mistook the proboscis for a male organ, which, however, he correctly located in a sheath between 

 the muscles of the body-wall and the digestive tract. The lateral fissures of the head he likewise 

 connected with the generative organs, and described and figured the nerves as semen-canals. 

 This appears to be an example of the Anopla, and hence we are enabled to predicate as to its 

 probable structure. 



In the same year (1830) Professor Leuckart, 6 in a further note on his Meckelia somatotomus, 

 calls the aperture of the proboscis the genital organ, but he correctly names the mouth. He 

 states that the genus Mechelia closely resembles Borlasia. 



In the following year (1831) our knowledge of the group received a considerable accession 



1 f Ann. des sc. nat./ Ire S£r., vol. 15, p. 140, pi. 5, figs. 25 and 26. 



2 ' Diet, des Sc. nat./ vol. 57, pp. 573—577. 1828. 



3 ' Zoological Journal/ vol. iv, 1829, pp. 56 and 57. 



^ < Ann. des sc. nat./ Ire Ser., vol. 21, p. 73, pi. 2, fig. 1—6. 

 ' Beschreibung und Anatomie eines neuen an Sicilien gefundenen Meerwurms.' Isis, 1830, heft. 

 6, pp. 681—3, taf. 7, figs. 1—6. 

 6 Isis, 1830, heft. 6, p. 575. 



