296 LIEUT. -COL. II. H. GODWIN-AUSTEK ON THE GENUS DTJBGELLA. 



List of Species of Durgella. 

 levicula, Bens. 

 assamica, Godw.-Aust. 

 seposita, Bens. ? Anatomy not examined. 

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

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

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

 sJiisTia, Grodw.-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 Macro clilainys. 

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

 pi. i. figs. 8 & 11, of Helicarion bicarinatus 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 over 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 D. assamica, much magnified : s, s, divisions 



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



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



in fig. 3. 



7. The sutural spiral of D. levicula. 



8. The sutural spiral of D. assamica. 



Plate XXI. 

 Fig. 1. Generative organs of D. 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 D. assamica. 



5. Jaw of D. levicula. 



6. Jaw of J), assamica. 



