296 LIEUT.-COL, H. H. GODWIK-AUSTEN ON THE GENUS DUEGELLA. 



List of Species of Durgella. 



levicitla, Bens. 



asscmica, Godw.-Aust. 



seposita, Bens. ? Anatomy not examined. 



mucosa, "W. & H. Blanf. ? Anatomy not examined. 



lurmanica, Bens. ? Anatomy not examined. I have very little 

 doubt about this shell, which I examined in the Benson collection. 



sTiislia, G-odw.-Aust. ? Anatomy not examined. 



It would have been supposed, taking the shell-character alone, 

 that Helicarion Bensoni, from the neighbourhood of Calcutta, would 

 come into this list; but I have the lingual ribbon of this species 

 from Mr. W. T. Blanford, and I find it similar to Macroclilamys. 

 Similarly, taking the figures in Semper's ' Eeis. Arch. Philipp.' 

 pi. i. figs. 8 & 1.1, of Helicarion hicarinatus and H.gutta, the shells 

 are very much like that of D. levicula ; but they appear to have, 

 besides the ordinary dentition, a different form of mucous pore 

 and more complicate shell- and mantle-lobes. The same applies 

 to H. tigrinus and H. incertus. 



EXPLANATION OF THE PLATES. 

 Plate XX. 

 Figs. 1 & 2. Shell of Durgella levicula, Bens. 



3. Animal (spirit-specimen) : r.s.l., right shell-lobe (the dotted line 



shows where it spreads oyer the shell when the animal is alive) 

 a.o., anal orifice ; r.o., respiratory orifice ; r.ap., renal aperture 

 r.d.L, right dorsal lobe ; l.d.l., left dorsal lobe ; s, lateral line 

 p, the central pedal area. 

 3 a. Extremity of foot ; lobe above the mucous pore, as in life. 



4. l.s.l, left shell-lobe; l.d.l, left dorsal lobe. 



5. Portion of side of foot of P. assamica, much magnified : s, s, divisions 



of the lateral line; s*, segmental lines running from it. 



6. Diagrammatic view of the mantle-lobes of P. assamica : lettering as 



in fig. 3. 



7. The sutural spiral of P. levicula. 



8. The sutural spiral of P. assamica. 



Plate XXI. 

 Fig. 1. Generative organs of P. levicula : P., penis; r.m.p., retractor muscle 

 of penis ; am.o., amatory organ ; r.m., retractor muscle ; v.d., vas 

 deferens ; sp., spermatheca ; ov., oviduct. 



2. Generative organs of D. assamica : h.d., hermaphrodite duct ; al.g., 



albumen-gland; ov., oviduct; sp., spermatheca; v.d., vas deferens 

 P., penis ; r.m.p., retractor muscle of penis. 



3. 3 a. Central laterals of D. levicula. 



4. 4 a. Central laterals of ID. assamica. 



5. Jaw of .P. levicula. 



6. Jaw of P. assamica. 



