VEKMES. 



51 



A few species are found in damp earth or in fresh water, others 

 are inquilines in Holothurioidea or in the respiratory cavities of 

 Ascidians. s 



Ehrenberg, M c lntosh, and others, rank the Turbellaria as a 

 class ; and it is variously divided. The families below are dis- 

 tributed under three sections : Dendrocrela with a ramified 

 digestive cavity, Khabdocoela with a simple one, both being with- 

 out an anal aperture (Aprocta), and Rhynchocrela with an anal 

 aperture (Proctucha) and the pharynx (proboscis) protrusible 

 and furnished with stylets. The first two sections also form the 

 suborder Planaricla of some systematists, distinguished by their 

 oval or elliptic form ; the third section, constituting the Nemer- 

 toidea, have an elongated linear form, one Lineus marimis (the 

 sea long- worm) sometimes attaining a length of 200 feet 

 [M e lntosh~\. Of the Planariidas some are very minute. Geo- 

 planidae comprise the " land-planarians." 



Pelagonemertes is a transparent leaf -shaped animal with a den- 

 drocoele intestine. Pterosoma appears to be an allied form. 



Balanoglossus, forming the class Enteropneusti of Gegenbauer, 

 has a complex branchial apparatus. Tornaria is supposed to be 

 its larval form. Mitraria is also supposed to be a larval form 

 belonging to this order. Convolutidse constitute the order Acrela 

 of Ulianin, and is adopted by Schmarda. 



Dendroccela are divided by Stimpson into Monogonopora (single 

 sexual aperture), including Planariidae and Geoplanidse ; and 

 Digonopora (double sexual aperture), including Eurylepiida?, 

 which has been split up into many families. Rhynchoccela are 

 also divided into Enopla (proboscis armed with stylets) =Amphi- 

 poridae, and Anopla (proboscis unarmed), including the remain- 

 ing families. These have mostly received character-names. In 

 this order there is very little accord between Schmarda and 

 Claus as to the position of the genera or to the sequence of the 

 families. In the Rhynchocoala, M c lntosh's classification has been 

 adopted. 



