202 BEV. R. T. Lowe's list or shells 



rather broader, and the sides or lateral outlines altogether more 

 convex and less parallel. The whole surface is equably and finely 

 decussated with spiral lines crossing the close, distinct and even 

 striae of growth, which are not conspicuously, as in B. decollatus 

 (L.), stronger or coarser at the sutures than elsewhere. The 

 outer lip is slightly expanded downwards, with a distinct, broad, 

 thickened rib or welt inside. The whole interior of the aperture 

 is of the same livid or purplish brown or fawn-colour as the rest of 

 the shell, which is of an altogether thicker, stronger, heavier sub- 

 stance, and more opake than is usually the case in S. decollata (L.). 



Named to record the assiduous zeal and energy of the Baron do 

 CasteUo de Paiva, a distinguished Portuguese naturalist and col- 

 lector, who, although chiefly devoted to botanical researches, is a 

 no less ardent than generous cultivator and encourager of other 

 branches of natural science. 



Pfeiifer's diagnosis of jB. decollatus (L.), by the words " ruguloso- 

 striata, lineis concentricis obsolete decussata," and " aufr. convex- 

 iusculis," seems to have been drawn up principally from the obso- 

 letely decussated state or var, of B. decollatus (L.) and the present 

 species, which is certainly his African var. /3. major, 39 millim. 

 long and 11 wide, &c. 



I subjoin the diagnosis of B. decollatus (L.), not only for the 

 sake of contrast, but because it may help towards the discovery of 

 this sheU at Mogador. 



Bulimus decollatus (L.). 



T. rimata adulta decollata angustato-cylindrica apice truncata tenuiuscula 

 subpellucida ochraceo-carnea v. cretaceo-alba laevigata striolis incre- 

 menti inaiquahbus crebriusculis infi-a suturam rudiusculis lineave 

 spirali impressa obsolete expressis, striolis spiralibus exilissimis tenuis- 

 sime vel obsolete ssepe decussata ; anfr. 4-6 planatis sutura distincta 

 parum impressa nee constricta ; cet. fere ut in B. Paiv<e sed char, 

 omnibus minus expressis obsoletioribus. 



Long, (adult, decoll.) 10-14 vel 15 ; diam. 4^-5 ; apert. long. 4^, lat. 

 2i lin. 



a. laevigata. Striis increment! exoletis insequalibus, spiralibus nuUis. 



B. decollatus, Drap. 76, t. 4. f. 27, 28 ; Gray, Man. p. 5, t. 6. 

 f. 60 ; Phil. i. 139 ; Eossm. v. vi. 45, f. 384 ; Sowerb. Conch. Man. 

 f. 289 ; Webb ! Syn. 14. no. 1 ; Orb. Moll. Can. in W. B. Hist. ii. 

 2. 68 ; Lowe ! Prim. 62. no. 61 ; Catal. Moll. Mad. in Proceed. 

 Zool. Soc. 1854, 199. no. 101; Kiist. M. et C. t.ll. f. 5-8, 1. 12. f.l3- 

 20. Helix decollata, Linn. Syst. (ed. 12) 1247 ; MiiU. Verm. ii. 114; 

 Chemn. ix. 2. 182, t. 136. f 1254, 1255; Hani. Conch. Linn. 379. 



