HISTORY OF THE SUBJECT. 17 



from the labours of the illustrious Ehrenberg, 1 who formed them with others into a distinct class, 

 which he termed Phytozoa Turbellaria. It is true he included under this head animals, such 

 as the Gordii and Naidina, which are widely dissociated from the typical group, and, in his 

 arrangement, placed apart genera allied in the closest manner, yet his contribution forms an 

 epoch in the literature of the Nemerteans. He characterised the Turbellaria briefly as " E ver- 

 tebrate apodous animals, creeping ; often with retractile vibratile hairs ; with a distinct intes- 

 tinal tube ; separate vessels without hearts, rarely with a mobile dorsal and abdominal vessel ; 

 hermaphrodite or with distinct sexes, oviparous and spontaneously fissile; excreting a copious 

 mucus." The Nemerteans were placed entirely under his second order, Rhabdoccela, that is, 

 Turbellaria with a simple cylindrical or conical intestine, having the mouth at one end and 

 the anus at the other. The family Micrurea he grouped under the second section (Monosterea) 

 along with the Gordii, but he more consistently classed all the other Nemerteans described by 

 him under the third section, AmpMporina. His arrangement is thus, as follows : — 



Section II. — Monosterea. 



Earn. Micrurea. 



Gen. Disorus, Micrura, and Polystemma. 



Section III. — Gyratricina. 



Gen. Orthostoma, Gyratrix, Tetrastemma, Prostoma, Hemicyclia, Ommatoplea, Am- 



phiporus. 

 Earn. Nemertina. 

 Gen. Nemertes, Notogymnus. 



The want of an anatomical basis for his classification rendered errors unavoidable, but his 

 descriptions of the species are characterised by care and lucidity, and his figures arc good. 

 He erroneously considered the proboscis to be the intestinal canal, and its aperture the mouth, 

 while the actual mouth in the Anopla he termed the genital opening. In the Enopla he could 

 not of course find the latter. He correctly noticed the presence of an anus. Since he states 

 that he saw a reddish viscus in Tetrastemma Jlavidum on each side in front of the proboscis 

 (which reddish mass he took for an ovarium), it is probable he alludes to the ganglia. The stylet- 

 region of the proboscis entirely eluded his notice. 



The arrangement of this author is implicitly followed in the twelfth edition of Lamarck's 

 ' Histoire Naturelle des Animaux sans Vertebres/ 2 



Dr. George Johnston described and figured 8 in 1833 Carinetta annulata under the name of 

 Carinella trilineata. He was unacquainted with the previous description by Montagu in the 

 'Linnean Transactions/ Like many others he also called the proboscidian aperture the mouth, 

 while the true mouth escaped his notice. He rightly stated that the anus was terminal. 



Quoy and Gaimardin the same year give an account, with figures, of several Nemerteans in 

 their zoology of the ' Voyage de la Corvette 1' Astrolabe.' None of their species, however, seem to be 



1 ( Symbolse Physicse. Anim. everteb. exclus. insectis.' Ser. prima. Berolini, 1831. 



2 ' Hist. Nat. des Animaux sans Vert/ 12th edit., par Deshayes et H. M. Edwards, vol. iii, pp. 

 610—613. Paris, 1840. 



3 Loudon's < Mag. Nat. Hist./ vol. vi, p. 232. 



