SAGDA. 59 



Shell having the texture of Zonltes or Hyalinia, imperforate or 

 umbilicate, varying in form from depressed and subdiscoidal to 

 globose-conic or trochoidal ; whorls 6-9, narrow and slowly increas- 

 ing, the lad not deftexed in front. Aperture nearly vertical, lunate, 

 either with or without internal laminre; lip thin, sharp and simple, 

 slightly dilated or reflexed at the axis ; coluinella short, having a 

 callous fold, or thin and simple. Type S. cookiana Gruel., pi. 16, 

 figs. 11, 12, 13. (See also pi. 16, figs. 14-20). 



Animal viviparous, or oviparous with hard-shelled eggs. 



Foot extremely long and narrow (the sole in S. similis measuring 

 length 20, width 3 mill.), strongly granulated above, the tail having 

 an impressed median longitudinal line or groove, acute behind ; sides 

 of foot without longitudinal grooves, but marked by a zigzag line 

 (pi. 35, fig. 7) ; sole not divided longitudinally (pi. 35, fig. 8, S. 

 similis). 



Genital system much, elongated, the vestibule short. Penis long, 

 the vas deferens and a flaaellum inserted at its apex (pi. 35, fig. 2), 

 and an elongated appendix inserted at the lower third (appendix of 

 S. similis seen convoluted in the normal manner in pi. 35, fig. 2, 

 partially straightened out in pi. 35, fig. 3). Vagina long and nar- 

 row ; uterus larger, containing eggs or young shells; duct of sper- 

 matheca very long, expanded near the base (pi. 35, fig. 4, S. similis). 

 See also pi. 21, fig. 9, penis of S. cookiana, p. penis, a. appendix, r. 

 p. retractor muscle,//, flagellum. Fig. 10 shows the appendix parti- 

 ally uncoiled. 



Jaw thin, arcuate, smooth, with a slight median projection or none 

 in S. foremaniana, haldemauiana, jayana and cookiana (pi. 21, fig. 8). 

 In S. similis (pi. 35, fig. 6) it is thin, arched, and of the stegognath- 

 ous type, being composed of 27 narrow flat vertical plates, soldered 

 together, the outer imbricating edges of which are distinctly visible. 



Radula having the transverse rows of teeth nearly straight. 

 .Central teeth having a square basal-plate and three cusps, the meso- 

 coue longer than the basal-plate. Lateral teeth bicuspid, the meso- 

 cone long. Marginal teeth also bicuspid. (PI. 21, fig. 7, S. cook- 

 iana ; pi. 35, fig. 5, S. similis; pi. 35, fig. 1, 8. haldemaniana'). 



The jaw of foremaniana has been described by Semper, that of 

 haldemaniana and jayana by Binney, that of cookunm by myself; 

 all agree in being smooth (oxygnathous) as described above. The 

 jaw of 8. similis, examined by the writer, is of the plaited type. The 

 teeth of fon mnn inna are described by Semper, those of connedens, 



