468 ABIONID-ffl. 



SLUGS. 



It has been found convenient to deal with the land slugs 

 collectively. For their systematic position reference should be 

 made to the systematic index at the commencement of this 

 volume. 



Family ARIONID^E. 



Subfamily ARIONIN^E. 



Genus ANADENUS, Heynemann. 



Anadenus, Heynemann, Malak. Blatt. x, 1863, p. 138 ; Godwin- 

 Austen, Moll. India, i, 1882, p. 46. 



Original description (in German) : " Anadenus (without tail 

 gland). Body fused with the sole for the whole length. Mantle 

 covering the anterior part of the body. Respiratory orifice placed 

 behind the middle of the right side of the mantle. Genital orifice 

 behind the right upper tentacle. Two upper and two lower 

 retractile tentacles. Back flatly convex (without keel, without 

 tail-gland). Sole tripartite. Jaw with close transverse ribbing. 

 The curve of the transverse rows of the radula practically in a 

 plane. Tooth-plates rectangular with projecting sides. Central 

 tooth unilateral, triangular with lateral spines. Laterals scarcely 

 differing from central, with a lateral spine on the outer side. 

 Internal shell present, white, calcareous, without epidermis on 

 the margin. Nucleus lateral. 



" The animal superficially resembles our German Arions and 

 Limaces. It is -related to Avion, but only resembles Limax. Its 

 relationship with Arion is established by the jaw which has 

 transverse ribs as in Arion empiricorum. On the other hand 

 it differs in the following particulars : 



Arion. Anadenus. 



Caudal gland : present. absent. 



Respiratory orifice : in front of placed further back. 



middle of the mantle. 



Internal shell : absent. present, with distinct growth- 



(the mantle contains only lines. 



scattered calcareous particles). 



" The principal character in which Anadenus differs from Arion 

 is the absence of the caudal gland ; somewhat less weight must 



