CLASSIFICATION. 61 



he divides the Ctenobranchiates into two sub-orders : the Pro- 

 boscidifern, which he believes zoophagous. furnished with an 

 entirely retractile trunk, and the Rostrifera. having a contractile, 

 but not retractile, trunk, and sometimes very long, as in Strn- 

 thiolaria, which he supi)Oses phytophagous. 



This author has thus placed the sections of Toxogiossa, (xym- 

 uoglossa, Ptenoglossa and Ttenioglossa in these two sub-orders. 

 The small value of the retractile trunk as an ordinal character is 

 proved for example in the BuUidse ( Bulla vexillum, possessing a 

 very long retractile trunk). Odostomia has also a very long re- 

 tractile trunk ; and the rather short trunk of Janthina is vei-y 

 often retracted into the head. 



In a more recent work.* Dr. (rray has reunited all the Toxo- 

 giossa? in a single division Toxifera, still retaining for the other 

 divisions the separation into two widely removed sections. The 

 name of Cteuoglossa is changed to Ptenoglossa ; the name 

 Trapezodonta is proposed for the Coriocelhe, the teeth of which 

 do not appear to Prof. Morch to ditier from tlie Taenioglosste 

 except in the want of the two internal teeth on each side (1.0. 0. 

 1.0. 0. 1). Heteroglossa is proposed for the Cyclobranchiates. 



In 1854, Mfirch divided the cephalophora into five great 

 groups, namely : I. Rhipidoglossata (including the Cyelo- 

 branchs); II. Ptenoglossata ( Pulmonata, Tectibranchiata, Jau- 

 thinidse) : III. T*nioglossata (including Pneumonopoina and 

 Heteropoda ) ; IV. Ilamiglossata (Proboscidea of Troschel, 

 Odontogiossa and Rachiglossa of Gray); V. Toxoglossata (in- 

 cluding Pleurotoma and Terebra ). In 18.5T, M'irch reduced the 

 five principal divisions to three, namely : 



I. MusivoGLOSSATA (corresponding to tJie Ptenoglossata of 

 1856, but thus modified because this name has been used by M. 

 Troschel to characterize the group of Janthinj^? and Scalarife), 

 Pulmonata and Tectibranchia. 



II. Arthioglossata, including : 1. Ticnioglossata, 2. Ancis- 

 troglossata, .3. Toxoglossata. 



III. Rhipidoglossata, with tlie section Orthodonta (Cyclo- 

 branchiates). 



In 1861-2, circumstances having induced Prof. Morch to 

 study the Planarians, he was struck with their great affinity 



* Ouide to Brit. Mus., 1857. 



