THE NAUTILUS. 95 



Forms of fasciatus approach closely to the variety coniformis of 

 mauritianus, and the aperture of the former species is indifferently 

 smooth or finely ridged. It, therefore, becomes necessary to enlarge 

 the group. S. luhuanus has the epidermis thickly lamellose, almost 

 velvety. The sagittate bands are more numerous than in the pre- 

 ceding group. 



GROUP J (Canariam). 



Shell small, but solid ; posterior sinus absent, posterior canal a 

 sligltt groove in the calloused angle at the suture ; anterior sinus very 

 near the canal ; aperture finely ridged ; lip margin with an external 

 rib, but not expanded. 



S. ustulatus, dentatus, corrugatus and var. elegans, urceus (=flori- 

 dus), hcemastoma, hellii, scalariformis, maculatus. 



Distribution : Red Sea to Hawaii and Australia. 



In form and sculpture, 5. elcgans is very suggestive of Rimetta, but 

 the exaggerated canals of the latter genus sufficiently distinguish it. 



Sub-group J 2. 



Surface smooth or with low vertical folds, polished; lip sinus 

 almost merged into the canal ; body drawn out, narrowed. S. samar 

 (blilbulus, terebellatus). Distr.: Japan to Australia and Polynesia. 



The last two species are not before me, but apparently they are 

 allied to samar and indicate close affinity of this group with the fol- 

 lowing. The accessory sinuses developed in samar must not be con- 

 fused with the true lip-sinus. 



GKOUP K (Seraphs'). 



In this group, which need not be redefined, we find the culmina- 

 tion of the features incipient in samar. The lip-sinus is broad, basal 

 and merged in the canal. The beautiful color-forms of the single 

 protean living species of " Terebelhun" inhabit the Indo-Pacific re- 

 gion from Mauritius to Japan and the Fijis. 



GROUP L (Rimella). 



Not studied. The living forms inhabit Chinese and Philippine 

 waters. 



GROUP M (Rostellaria). 



Not studied. Red Sea to China and Moluccas. 



The groups above recognized are probably by no means all of equal 



